Research Article Organic Membranes for Selectivity...

Research ArticleOrganic Membranes for Selectivity Enhancement ofMetal Oxide Gas Sensors

Thorsten Graunke12 Katrin Schmitt3 and Juumlrgen Woumlllenstein13

1Laboratory for Gas Sensors Department of Microsystems Engineering-IMTEK University of FreiburgGeorges-Koehler-Allee 102 79110 Freiburg Germany2ams Sensor Solutions Germany GmbH Gerhard-Kindler-Strasse 8 72770 Reutlingen Germany3Fraunhofer-Institute for Physical Measurement Techniques IPM Heidenhofstraszlige 8 79110 Freiburg Germany

Correspondence should be addressed toThorsten Graunke thorstengraunkeamscom

Received 1 September 2015 Accepted 19 October 2015

Academic Editor Sheikh Akbar

Copyright copy 2016 Thorsten Graunke et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

We present the characterization of organic polyolefin and thermoplastic membranes for the enhancement of the selectivity of metaloxide (MOX) gas sensors The experimental study is done based on theoretical considerations of the membrane characteristicsThrough a broad screening of dense symmetric homo- and copolymers with different functional groups the intrinsic propertiessuch as the mobility or the transport of gases through the matrix were examined in detail A subset of application-relevant gaseswas chosen for the experimental part of the study H

2 CH4 CO CO

2 NO2 ethanol acetone acetaldehyde and water vapor

The gases have similar kinetic diameters and are therefore difficult to separate but have different functional groups and polarityThe concentration of the gases was based on the international indicative limit values (TWA STEL) From the results a simplerelationship was to be found to estimate the permeability of various polar and nonpolar gases through gas permeation (GP)membranesWe used a broadbandmetal oxide gas sensor with a sensitive layermade of tin oxidewith palladium catalyst (SnO

2Pd)

Our aim was to develop a low-cost symmetrical dense polymer membrane to selectively detect gases with a MOX sensor

1 Introduction

The reliable detection of toxic and flammable gases is ofhigh importance in many fields of daily life for examplesurveillance of chemical processes or in the event of firesor disasters The early detection of toxic gas concentrationscan save lives and aid in taking appropriate countermeasuresA variety of different gas sensing technologies is used todetect these gasesThe choice of the right technology dependson the required sensitivity selectivity and last but notleast the costs A gas sensor is generally composed of areceptor (probe) and a transducer (signal transducer) If thesensor comes with integrated signal processing it is usuallycalled ldquosmart sensorrdquo Depending on the environment andapplication different gas sensing technologies are availablewhich are classified according to their physicochemicalfunctional principle (IUPAC 1991) into optical electrochem-ical conductivity ultrasonic magnetic thermometric and

mass-sensitive sensors [1ndash5] In reality all sensing technolo-gies are more or less prone to some drift effects susceptibleto interfering gases vapors or other uncontrollable memoryeffects These effects reduce sensitivity but also selectivityOne way to increase the selectivity of gas sensors in general isthe use of passive filter materials [6]

Passive filter materials are in most cases flat semiperme-able membranes that are permeable to at least one materialcomponent The membranes are characterized by the size ormolecular weight of the transmitted component the drivingforce the principle of separation and the present state ofaggregation Filters for microfiltration (MF) ultrafiltration(UF) and nanofiltration (NF) have pore diameters (119909) of 119909 gt

100 nm 10 nm lt 119909 lt 100 nm and 1 lt 119909 lt10 nm The statesof aggregation to be separated are liquidliquid solidliquidor solidgaseous Usually the separation is accomplishedby sieve mechanisms or sorption + diffusion mechanismsThe driving force is a pressure difference or a difference in

Hindawi Publishing CorporationJournal of SensorsVolume 2016 Article ID 2435945 22 pageshttpdxdoiorg10115520162435945

2 Journal of Sensors

the chemical potential In the separation of small moleculeswith diameters of less than 1 nm the reverse osmosis (RO)the diffusion dialysis (DD) or electrodialysis (ED) is usedas the membrane process for the physical state liquidliquidThe separation mechanism is based on a sorption + diffusionin the RO and DD In the ED the mechanism is based onelectrophoretic mobility The driving force is the differenceof the chemical potential (in RO) a concentration difference(in DD) or a difference in electrical potential (in ED) Ifthe physical state is liquidgas the method of choice ispervaporation (PV) The material separation proceeds via asorption + diffusionmechanismThe driving force is a partialpressure difference For separation of gaseous components(gasgas) vapor permeation (VP) and gas permeation (GP)are used The driving force here is a partial pressure just asin pervaporation The mechanism is based on sorption +diffusion In the VP the gases are under standard conditions(21∘C 1 bar) in liquid form and in gaseous form at the GP Forthemembranemethod of VP andGP a variety of commercialand in-process membranes is available Interesting for useas a selective filter in the gas sensors are synthetic solidmembrane materials These comprise organic inorganicor heterogeneous membranes Heterogeneous membranesconsist of a combination of organic and inorganic materials

The organic polymer membranes are in a rubbery-elastichard-elastic or glassy state depending on the glass transi-tion temperature The degree of crystallinity is amorphoussemicrystalline or ideal crystalline For the separation ofgases only dense polymer membranes or polymers havingintrinsic microporosity (PIM) can be used [7] In denseglassy polymer membranes the influence of diffusion is highcompared to the sorption For this reason preferably smallmolecules are transported independently of the polymerThepermeability decreases in the order C

3H8lt CH

4lt N2lt

CO lt O2lt CO

2lt He lt H

2lt H2O In rubbery polymers

the solubility determines the permeability [8] The perme-ability is significantly higher and preferably large moleculesare transported In elastomeric polymers the permeabilitydecreases usually in the order N

2lt He lt O

2lt H2

lt

CH4lt CO

2lt C3H8lt H2O [9] This results in an inverse

correlation Highly permeable elastomeric symmetric poly-mers are usually not very selective while glassy symmetricpolymers have a high selectivity and at the same time a lowpermeability When modified polymers can be adapted tospecific applications Thus a polymer can be functionalizedor its polarity that is hydrophobicityhydrophilicity can bealtered by a chemical modification In addition to a modifi-cation of the membrane material by integration of additivesto establish block- or comb-copolymers surface-controlledchemical modifications may be done One example is fixed-side carrier membranes where suitable carriers are bound ina polymer matrix By fixing of gas molecules a facilitatedselective mass transport through the membrane is achievedby hoppingmechanisms [10] Surface chemical modificationscan be achieved by adsorption without interfering with thestructure (ldquoself-assemblyrdquo coatings) by chemically modi-fying the base material or by using the base material forfurther functionalization The morphology of the polymer isnot or only minimally changed by derivatization grafting

or targeted degradation during chemical modification Thephysical activation is preferably done by UV radiation orplasma treatment During functionalization macromolecularfunctional units are introduced via grafting reactions This iseither a directed coupling by chemical reaction with reactivegroups on the surface (covalent ldquografting-tordquo) or a hetero-geneous radical graft copolymerization with the aid of fixedinitiator groups (ldquografting fromrdquo) Using these functionalgroups the surface properties can be optimized [11ndash14] withregard to polarity hydrophilicityhydrophobicity and theresistance to fouling

Using asymmetric polymers the permeability can beincreased by a factor of at least fifty up to one hundredwhile maintaining a constant selectivity Asymmetric poly-mers consist of a dense barrier layer having a thickness of005ndash05 120583m The separation layer is stabilized by a poroussupporting layer (30ndash200120583m) The pore size increases withdistance from the separating layer They involve integral-asymmetric membranes consisting of a polymer or com-posite materials in which the active layer and the supportlayer aremanufactured fromdifferentmaterials In compositematerials the properties of the individual layers can beoptimally adapted to a separation problem Since it is difficultto apply a thin release layer on a porous structure a smoothhighly permeable intermediate layer is often applied Verythin separation layers are prone to build up pinholes whichmay result in Knudsen diffusion or an unselective viscous gasflow Such pinholes can be sealed with a silicone coatingTheseparation factor is only minimally affected by such a coverlayer An overview of gas-selective polymer membranes isgiven in [9 15 16] in combination with gas sensors in [17 18]

On the other hand inorganic membranes for specialapplications of microfiltration (MF) and ultrafiltration (UF)are now established Among these are silica-based mem-branes of high importance [19ndash23] but also zeolites [24ndash30]Other materials involve perovskites [31 32] Al

2O3[19 33

34] or copper oxide [35] Compared to polymers inorganicmembranes have the following advantages the cut-off andseparation sharpness can be better controlled The mem-branes are characterized by a higher temperature resistancea lower aging and better chemical resistance (no membraneswelling) Among symmetric porous inorganic membranesfor gas separation the carbon membrane is important How-ever inorganic membranes have the following disadvantageslimiting their application as GP membranes the materialsare mostly brittle and require a multilayered structure whichalso involves several steps The production is therefore moreexpensive than for comparable polymer membranes There-fore themembranes are simply too expensive for applicationsin gas sensor technologyTherefore inorganicmembranes arenot described here in detail instead we refer to overviews ofgas-selective inorganic membranes given in [36 37]

Another class the so-called mixed matrix membranes(MMM) consists of a combination of inorganic and organicmaterials [38ndash40] The selectivity and the permeability ofthe membrane can be calculated in advance from the dataof the homogeneous materials The company Creavis pro-vides flexible ceramic flat membranes under the trade nameCreafilterThismembrane consists of a supportmade ofmetal

Journal of Sensors 3

or plastic fabrics on which ceramic particles are applied in anasymmetric structure Pore sizes in the separation layer cannow be realized from 05 to 5 nm A further possibility is theincorporation of inorganic particles into a polymer matrixforming the separation layer Inorganic materials used aremolecular sieves (zeolites such as LTA AlPO SAPO SSZ-13and ZSM-5) porous metals (MOM metal organic material)pyrolyzed polymers (CMS carbon molecular sieve) meso-porous molecular sieves silicates metal oxides activatedcarbon nanotubes (NT nanotube) or also liquids [41] Thisoverview is adapted from [42ndash44] Further details on GPmembranes can be found in [45ndash51]

Due to the industrial applications of GP membranesprimarily the binary gas mixtures O

2N2 N2CH4 SO2CH4

H2N2 HeN

2 CO

2N2 CO

2CH4 H2CO2 SO2CO2

H2CO and H

2CH4are of interest In connection with

carbon membranes occasionally separation factors for thebinary mixtures C

2H4C2H6 H2n-C4H10 C3H6C3H8can

be found In many applications the influence of air humid-ity on the performance of polymers is of significance Sothe permeability for CO

2and CH

4from Matrimid and

polysulfone (PS) in humid air decreases greatly [52] Forthe separation of volatile organic compounds (VOC) themethods of pervaporation (PV) and vapor permeation (VP)may be used The substances to be separated are in a liquidor vaporous state respectively The separation is determinedas in the GP mainly by the interaction of the componentwith the membrane Therefore the most important factorsare the solubility and diffusion For all three methods thesame membranes can be used Hydrophilic membranes areused for the vapor permeation and for the separation ofpolar components Applications are the drying of ethanol(H2OEtOH) or methane (H

2OCH

4) Organophilic mem-

branes have a high affinity towards nonpolar substances Animportant application is the removal of VOCs from waterAmong these VOCs are toluene n-butanol n-propanolethanol acetone and methylene chloride For the sepa-ration of organic mixtures (VOCgas) less highly cross-linked hydrophilic membranes such as poly(1-trimethylsilyl-1-propyne) (PTMSP) polyoctylmethylsiloxane (POMS) andpolydimethylsiloxane (PDMS) are used [53ndash58]

Despite the enormous amount of polymer membranesthat are available and the many new developments inthe field of membrane GP only 8 to 9 polymers havea market share of 90 These are polyimide (PI) poly-sulfone (PS) polyaramid (PA) polycarbonate (PC) cellu-lose acetate (CA) polyphenylene oxide (PPO) and fluo-ropolymers Important representatives of the fluoropoly-mers are polytetrafluoroethylene (PTFE) polychlorotrifluo-roethylene (ECTFE) and fluorinated ethylene-co-propylene(FEP) The only representatives of the elastomeric poly-mers are silicones like PTMSP PDMS and POMS Thesepolymers are used in the following industrial separationprocesses PI (H

2CO) (H

2CH4) (O

2N2) (CO

2N2)

(CO2CH4) (H2OCH

4) (H2OLuft) PS (H

2N2) (O2N2)

(H2CO) (H

2CH4) PA (H

2OCH

4) (CO

2CH4) PC

(O2N2) CA (O

2N2) (H2OCH

4) (CO

2CH4) (H2CH4)

(H2CO) (H

2N2) PPO (O

2N2) (CO

2CH4) fluoropoly-

mers (CO2CH4) (N2CH4) silicones (H

2CO) (H

2CH4)

(O2N2) (N2CH4) (VOCGas) The first gas listed has the

highest permeability through the polymer membrane [9 1648 55 59]

In our study we investigated the permeability of gasesincluding H

2 CO CO

2 NO2 methane ethanol acetone

acetaldehyde and moisture through low-cost symmetricalpolymeric materials having a diameter of less than 64mmDue to the small diameter the membranes can be directlyintegrated into the metal caps of conventional TO socketsThe mass transfer takes place at room temperature andwithout partial pressure The permeate is not removedThrough a broad screening of dense symmetric homo- andcopolymers with different functional groups the intrinsicproperties such as the mobility or the transport of gasesthrough the matrix were examined in detail The gaseshave similar kinetic diameters and are therefore difficult toseparate but have different functional groups and polarityThe concentration of gases is based on the internationalindicative limit values (TWA STEL) From the results asimple relationship is to be found to estimate the permeabilityof various polar and nonpolar gases through GPmembranesWe used a broadband metal oxide gas sensor with a sensitivelayer made of SnO

2Pd Our aim is to develop a low-cost

symmetrical dense polymer membrane to selectively detectgases with aMOX sensor Althoughmany studies exist on theinvestigation of single polymeric membranes for selectivityenhancement of sensors we believe that this is the firststudy to systematically compile all relevant polymers for thisapplication The use of the same experimental conditionsthroughout the study enables us to compare the differentpolymers and understand the characteristics and mecha-nisms leading to their separation properties

2 Materials and Methods

21 Polyolefins and Thermoplastics In this study polyolefinsand thermoplastic polycondensateswere tested for their sepa-ration propertiesThe structures of the polymers are shown inFigure 1 From the group of polyolefins we used membranesmade of polyethylene (PE) low density polyethylene (LDPE)high density polyethylene (HDPE) and graphite filling(PE + graphite) as well as polypropylene (PP) and poly-4-methylpentene-1 (PMP) These materials are characterizedby high chemical resistance low density and low watervapor permeability PE is a nonpolar partially crystallinethermoplastic Due to the diversity in structural composi-tion such as chain length molecular weight or degree ofbranching the various PE grades differ in their propertiesLDPE is a widely branched homopolymer containing bothshort- and long-chain branches and thus having an enlargedmolecular distance compared to other PE types This resultsin crystallization degrees between 40 and 50 and a densityof 092 gcm3

The crystalline melting point is between 105∘C and 110∘CThe water intake is low with 0015 In LDPE two glasstransitions are observed at minus110∘C and minus10∘CThe continuousoperating temperature is between 50∘C and 90∘C the lowestof all investigated polymer membranes and still adequatefor use in gas sensors HDPE is made up largely of linear


CC

H H

HHn

lowast lowast

(a)

CH

n

lowast lowastCH2

CH3

(b)

CHn

lowast lowastCH2

CH3

CH3

(c)

n

lowast

lowastCH3

CH3

O

O

O

(d)

n

lowast lowast

O O

OO

(e)

nlowast

lowast

O

O

OO

(f)

n

lowast lowastO O C

O

(g)

H

n

lowastlowast

O

N

(h)

nlowast

lowast

O

O

O

O

O

N

N

(i)

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

(j)

n

lowast lowastS

O

O

O

(k)

Figure 1 Molecular configurations of homopolymers used (a) polyethylene (PE) (b) polypropylene (PP) (c) poly-4-methylpentene-1(PMP) (d) polycarbonate (PC) (e) polyethylenterephthalat (PET) (f) polyethylene naphthalate (PEN) (g) polyetheretherketone (PEEK)(h) polyamide (PA6) (i) polyimide (PI) (j) polyetherimide (PEI) and (k) polyethersulfone (PES)

macromolecules having a low degree of branchingThis leadsto a higher degree of crystallization of 60 to 80 andaccordingly a higher density of 095 gcm3 With increasingdensity the swelling and permeability decrease HDPE showspractically no water absorption (lt001) In contrast thecrystalline melting point (130ndash135∘C) rises as well as thecontinuous operating temperature (55ndash120∘C) Both HDPEand LDPE have a glass transition around minus110∘C The PEmembrane with graphite filling has a density of 096 gcm3The addition of graphite increases the chemical resistance PPis a semicrystalline nonpolar polymer

The degree of crystallization is essentially determinedby the tacticity of the macromolecular chains The isotacticPP has due to the regular arrangement of the methyl sidegroups the highest degree of crystallinity (60ndash70) PP showscrystal modifications of the 120572- 120573- and 120574-modification and

mesomorphic (smetic) forms In the crystalline domains themacromolecules are in the form of folded chains as lamellaeThewater uptake is onlyminimally higher than that of HDPEwith lt005 The density is a result of the increased distancesby -CH

4side group with 09 gcm3 less than for LDPE The

statistically measured glass transition temperature is minus10∘CThe crystallite melting range is from 160∘C to 168∘C PP filmshave an upper continuous operating temperature of 100∘CPMP is a semicrystalline largely isotactic thermoplastic Thebulky side group leads to a crystalline melting point of 236∘Cand to an unusually low density of 083 gcm3 PMP has thelowest density of all thermoplastics At room temperaturethe amorphous domains are denser At a temperature of60∘C both states have the same density Due to the differentcoefficients of thermal expansion there is a cavity formingbetween the amorphous and crystalline areas The water


absorption is below 001 PMP has two glass transitions atminus55∘C and between +50∘C and +60∘CThe upper continuousoperating temperature is 120∘C [60ndash62]

The second group which was examined with respect totheir separation properties is thermoplastic polycondensatesIn this group themembranes aremade of polycarbonate (PC)polyethylene terephthalate (PET) polyethylene naphthalate(PEN) polyether ether ketone (PEEK) polyamide (PA6)polyimide (PI) polyetherimide (PEI) and polyethersulfone(PES) PC PET and PEN are thermoplastic polyesters PC isa purely amorphous linear thermoplastic The ester groups(-COOR) are polar and are separated by aromatic groupsThe polarity leads to water absorption of 015 to 035 Theangled and bulky repeating unit restricts the mobility ofthe macromolecules This leads to a high glass transitiontemperature of 148∘C The operating temperature is 125∘CThe density is 12 gcm3 Films can be cast with a minimumthickness of 2120583mfromsolutions PET crystallizes very slowlyTherefore it may be amorphous or semicrystalline with adegree of crystallization of 30 to 40 The average glasstransition temperature is 98∘C The melting temperature is250ndash265∘C The water absorption is 01 higher than that ofthe polyolefins however lower than that of PC The densityvaries between 13 gcm3 in the amorphous and 14 gcm3in the semicrystalline state The operating temperature isbetween 115∘C and 150∘C In PEN the polar ester groups(-COOR) are separated from each other by bicyclic nonpolararomatic groups (naphthalene) As a result the crystallinemelting temperature is increased to 270∘C (250∘C to 265∘Cin PET) the glass transition temperature is higher at 122∘C(PET 98∘C) and the continuous operating temperature risesto 155∘C (PET 115∘C to 150∘C) By quenching in ice watera low degree of crystallization of asymp5 is achieved As afilm PEN is amorphous and biaxially oriented and has adensity of 136 gcm3 PEN shows compared to PET highergas tightness and improved mechanical properties as wellas greater resistance to hydrolysis and chemicals The waterabsorption is 04 significantly higher than in PC and PET

By a direct linear linking of aromatics via ether andcarbonyl (ketone) bridges (eg in PEEK) via imide or etherbridges (eg in PI and PEI) or via ether or sulfone bridges(eg in PES) polymers are obtained with very high thermalstability and improved chemical and physical propertiesThisis because the binding energy is higher than that of simpleCC chains PEEK belongs to the group of aromatic polyetherketones With an increasing number of ether groups (flex-ibility) in polyether ketones the glass transition point andmelting point decrease (PEEEK gt PEEK gt PEK = PEEKKgt PEKEKK gt PEKK) The glass transition temperature ofPEEK is 143∘C The crystalline melting point is 334∘C Thedensity varies between 126 gcm3 in the amorphous and132 gcm3 in the semicrystalline state PEEK has a maximumdegree of crystallization of 48Thin filmsmade of PEEK areamorphouswith a density of 126 gcm3Thewater absorptionis 01 to 03 lower than that of PEN PEEK has a veryhigh continuous operating temperature of 250∘C and isone of the high-performance plastics PA6 belongs to thegroup of aliphatic polyamides The properties of polyamides

are essentially determined by the carboxamides and thenumber of methylene groups between the carboxamides Adistinction is made between two types the AB-polyamidesand the AABB polyamides PA6 is an AB polyamide Thenumber of -CH

2- groups between recurring carboxamide is

five In the linear PA6 macromolecules only every secondfunctional group allows a hydrogen bond The density is113 gcm3 and the water absorption 27With an increasingnumber of methyl groups the density and water absorptiondecrease in polyamides (eg PA6 gt PA11 gt PA12)The degreeof crystallization is 50 to 60 The crystalline meltingpoint of PA6 is 230∘C In general polyamides with an evennumber of -CH

2- groups melt at higher temperatures than

those with an odd number (eg PA11 gt PA12) The operatingtemperature is between 80∘C and 100∘C The glass transitionin PA6 is highly moisture-dependent Dry PA6 has a glasstransition temperature of 60∘C With a moisture content of35 the transition temperature shifts to 5∘C and at 10 eventominus15∘C Polyamides are highly polar because of the -NH andgtC=O groups

In the first stage of manufacture the PI macromoleculesare in a chain form thus linear without cross-links In the sec-ond reaction stage (cyclizing condensation polymerization)however often cross-links form The structure is thereforelinear or cross-linked (thermoset) amorphous and polarThe monomer consists of an imide and a phenol group Thethready arranged macromolecules which consist primarilyof aromatic and heterocyclic ring compounds are tightlyarranged This results in a continuous operating temperatureof 250∘C a high stiffness and hardness a satisfactory resis-tance to chemicals and water and high flame retardancy PIis not meltable (carbonization at 800∘C) The glass transitiontemperature is between 250 and 270∘C The density of PIis 142 gcm3 PEI is a linear amorphous thermoplastic andlike PI significantly polar The two ether bridges in themonomeric building block of PEI cause increased flexibil-ity This leads to a reduction of the continuous operationtemperature to 170∘C to 200∘C (for comparison PI has250∘C) the glass transition temperature is 215∘C (PI 250∘Cto 270∘C) and the density is 127 gcm3 (PI 142 gcm3)The water absorption remains virtually unchanged at 025PES is a member of the so-called polyarylsulfones PEScontains a sulfone (-SO

2-) and in the 14 position linked

phenyl rings and an ether linkage PES is amorphous andsubstantially polar because of diphenyl sulfone The bulkystructure prevents any formation of crystals in the meltThe aromatic compounds in PES lead to a high continuousoperating temperature of 180∘C to 220∘C Due to ethergroups the polymer chain is more flexible Thereby the glasstransition temperature is reduced compared to polysulfonyl-14-phenylene to 225∘C The density is 137 gcm3 With 04to 1 PES shows the highest water consumption of all poly-mers investigated Characteristic properties of PES are highstrength stiffness hardness and high resistance to chemicalsand hydrolysis [63ndash68] The polyolefins and thermoplasticpolycondensates were obtained from Goodfellow (GF) andReichelt Chemietechnik (RCT) These companies providephysical and chemical data on their polymers [69 70]


Table 1 Selected structural thermal andmechanical properties of the homopolymers used in our study dc refers to the degree of crystallinitythe glass transition temperature is 119879G 119879M is the crystallite melting point 119879CO is the continuous operating temperature and WA is waterabsorption in 24 h based on weight percent the density 120588 and Δ119911 the thickness of the membrane sheet Adapted from data sheets of thesuppliers Goodfellow (GF) and Reichelt Chemietechnik (RCT) [69 70]

Polymer Structure at 119877119879 (21∘C) 119879G [∘C] 119879KS [∘C] 119879DG [∘C] WA [24 h m] 120588 [gcm3] Δ119911 [120583m]

LDPE Partially crystalline(dc 40ndash50)

ltminus110minus10 105ndash110 50ndash90 lt0015 092 10

(GF)

HDPE Partially crystalline(dc 70ndash80) ltminus110 130ndash135 55ndash120 lt001 095 10

(GF)

PE + graphite Partially crystalline mdash mdash mdash mdash 096 80(RCT)

PP Partially crystalline(dc 60ndash70) minus15 160ndash168 100 lt005 09 10

(RCT)

PMP Partially crystalline(dc 65) minus55 50 236 120 lt001 083 50

(GF)

PC Amorphous 148 mdash 125 015ndash035 12 20(RCT)

PETAmorphous or partially

crystalline(dc 30ndash40)

98 250ndash265 115ndash150 01 13 (amorphous)14 (crystalline)

13(GF)

PENAmorphous or partially

crystalline(dc asymp 5)

122 267 155 04 136 12(GF)

PEEKAmorphous or partially

crystalline(dc le 48)

143 334 250 01ndash03 126 (amorphous)132 (crystalline)

12(GF)

PA6 Partially crystalline(dc 50ndash60)

minus8 2855 230 80ndash100 27 113 15

(GF)

PI Amorphous 250ndash270 mdash 250 02ndash29 142 8(RCT)

PEI Amorphous 215 mdash 170ndash200 025 127 25(GF)

PES Amorphous 230 mdash 180ndash220 04ndash10 137 25(GF)

These were compared with the literature references Table 1gives an overview on the physical and thermal properties ofpolyolefins and thermoplastic polycondensates necessary forthe description of the separation of substances The selectedpassive membranes thus meet the following criteria themembranes can be used in a temperature range fromminus20∘C toat least +90∘Candhave a sufficiently high chemical resistanceThe membrane materials have a similar layer thickness sothat the release properties can be compared The separa-tion properties of a polymer membrane are significantlydetermined by their structure (amorphous harr crystallinebranched harr linear) the resulting degree of crystallizationthe density (low density is synonymous with large atomicdistances) the polarity (polar harr nonpolar) and the waterabsorption as a measure of the polarity and through the glasstransition point and the crystalline melting point So forexample the densities of the selected polymer membranesvary between 083 gcm3 (polymethylpentene) and 14 gcm3(polyimide) and the water absorption varies between lt001(HDPE and PMP both nonpolar) and sim27 (PA6 and PIboth polar) These are commercially available materials andthus potentially low-priced filter materials

22 Solution-Diffusion Model in Polymer Membranes Themass transport in porous dense polymer membranes isdescribed by the solution-diffusion model Here the polymeris treated as a real liquid in which dissolved gas moleculesdiffuse in the direction of a gradient A measure of thesolubility is generally given by the boiling points and criticaltemperatures of the gasmoleculesThemass transfer througha nonporous membrane is therefore equal to the product ofconcentration mobility and a driving force

Flow = concentration sdotmobility sdot driving force (1)

The mobility of gases within a polymer structure depends onthe size of the gas molecules and the membrane propertiessuch as the glass transition temperature (119879

119866) and the free

volume (119881119898119891) The driving force for mass transfer is the

gradient of the chemical potential within the membranephase minus119889120583

119894119889119911 where 119911 is in the direction perpendicular to

the membrane surface The driving force is a function of thethermodynamic quantities mole fraction (119883

119894) pressure (119901

119894)

and temperature (119879) in the outer permeate and feed phaseThe concentration depends on the partition equilibrium


Solution-diffusion process

Gas A

Gas B or polymer segment

Sorption Feed Diffusion

Permeate

Vmf

(a)

Feed

Membrane

PermeateΔz

pf

120583fgi

Xfi

pfi

Cfmi

Cpmi

Xpi

ppi

pp

120583pgi

Ji

120583pi minus 120583

fi

(b)

Figure 2 (a) Schematic representation of the solution-diffusion process of amolecule (A) through a polymermatrixThe diffusion takes placein the free volume (119881119898

119894) To avoid reverse diffusion the free position has to be occupied by another molecule or a polymer segment (B) (b)

The transport through a solution-diffusion membrane consists of three relevant steps sorption diffusion and desorption (120583 designates thechemical potential119883 is the mole fraction 119862 is the concentration 119901 is the partial pressure 119869 is the flux 119911 is the layer thickness the subscript 119894indicates a material component and the superscripts 119891 119901 119892 and119898 indicate the material component in the feed (119891) the material componentin the permeate (119875) the physical state (gaseous 119892) and the membrane matrix (119898))

and the activities in feed and permeates This is shownschematically in Figure 2

The mass transfer through a dense polymer membranehas three important steps In the first step a sorption ofvarious molecules according to the distribution coefficientsof the feed phase takes place The second step is the diffusionthrough the membrane matrix The difference between thechemical potentials 120583119901

119894minus 120583119891

119894is always greater for a retained

component than for a permeating component The rate ofdiffusion of individual components of a substance mixturethrough a dense membrane is primarily determined by therespective product of solubility and mobility rather than bythe driving forces The ratio is thus also a measure for theselectivity In the last step desorption of the components intothe permeate phase takes place

The general form of the transport equation for thesolution-diffusion model is

119869119894= minus119862119898

119894sdot 119887119898

119894sdot

119889120583119898

119894

119889119911

(2)

A relationship between the mobility 119887119898

119894and the thermody-

namic diffusion coefficient 119863119898119894is provided by the Nernst-

Einstein equation

119863119898

119894= 119877 sdot 119879 sdot 119887

119898

119894 (3)

Here 119877 denotes the universal gas constant and 119879 is thetemperature This can be further expanded to the diffusionequation

119869119894= minus119862119898

119894sdot

119863119898

119894

119877 sdot 119879

sdot

119889120583119898

119894

119889119911

= minus119871119894sdot

119889120583119898

119894

119889119911

(4)

Here 119869119894is the flux 119871

119894is a phenomenological constant 120583 is the

chemical potential and 119911denotes the direction perpendicularto the membrane surface The superscript 119898 refers to themembrane and the subscript 119894 to a substance componentAssuming that there is a chemical equilibrium at the phaseboundaries between the membrane surface and feed orpermeate phase the change in the chemical potential of amaterial component is provided as a function of pressure atconstant temperature

119889120583119894

119889119911

=

1

119889119911

sdot (119881119894119889119901 + 119877119879119889 ln 119886

119894) (5)

where 119886 is the activity 119901 is the pressure and 119881 is the partialmolar volume Thus the following relationship for the flux 119869

119894

can be derived

119869119894= minus119871119894

1

119889119911

(119877119879119889 ln 119886119898119894+ 119881119894119889119901) (6)


Assuming further that the pressure inside the membrane isconstant (119889119901 = 0) the second term is omitted and the flux isgiven by

119869119894= minus119871119894119877119879

119889 ln 119886119898119894

119889119911

=

119871119894119877119879

119886119898

119894

sdot

119889119886119898

119894

119889119911

(7)

The integration of (7) gives the flux as a function of the activityof a substance component 119894 between the feed and permeatephase

119869119894= minus119871119894

119877119879

119886119898

119894

sdot

119886119898119901

119894minus 119886119898119891

119894

Δ119911

(8)

where 119886119898119894is the average activity and Δ119911 is the layer thickness

of the membrane The superscripts 119898 119891 and 119901 refer tothe phase boundary between the membrane surface and theadjacent feed and permeate phase A correlation of the phaseboundary to the gas phase (119892) is given by

119886119898119891

119894=

119886119892119891

119894sdot 119901119891

1199010

119894

119886119898119901

119894=

119886119892119901

119894sdot 119901119901

1199010

119894

(9)

Therein 119901 denotes the vapor pressure and 1199010the saturation

vapor pressure of a substance component (119894)The superscripts119891 and 119901 refer to the feed and permeate Substituting the twocorrelations in (8) we obtain for the flux (119869

119894) the following

expression

119869119894= minus119871119894

119877119879

119886119898

119894sdot1199010

119894

sdot

119886119892119901

119894sdot 119901119901minus 119886119892119891

119894sdot 119901119891

Δ119911

(10)

With the definition of concentration (119862119898119894) of a substance

component 119894 in the membrane the relationship betweenthe phenomenological coefficient (119871

119894) and the diffusion

coefficient (119863119898119894) is

119862119898

119894=

120588119898

119894

119872119894

sdot

120593119894sdot 119901119894

120574119894sdot 1199010

119894

=

120588119898

119894

119872119894

sdot 119883119898

119894 119871119894=

119863119898

119894sdot 119862119898

119894

119877119879

(11)

With the assumption that the fugacity coefficients in perme-ate and feed are the same (120593119901

119894= 120593119865

119894) we obtain from (10)

119869119894= minus119863119898

119894sdot

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

= minus119863119898

119894sdot 119896119894sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

(12)

where 119863119894is the coefficient of diffusion 120593

119894the fugacity

coefficient 120588119894the density 120574

119894the average activity coefficient 119901

the pressure119872 the molecular weightΔ119911 the thickness of themembrane and 119896

119894the sorption coefficient The superscripts

119901119891119898 and 0 refer to permeate and feed the membrane anda state of equilibrium The product of diffusion and sorptioncoefficients is called the permeability coefficient (119875

119894)

119875119894= 119863119894sdot 119896119894 (13)

The two coefficients for the diffusion (119863119894) and sorption

(119896119894) represent the most important parameters describing

the release properties of dense polymer membranes Thediffusion coefficient depends on the membrane structure(mutual disposition and dynamics of polymer segments)the size of the permeating substance components and thetemperatureWith the proviso that no phase transitions in thepolymer matrix or in the penetrant take place (such as glasstransition point or boiling point) and the permeate pressureis less than the saturation vapor pressure the temperaturedependence of the diffusion coefficient can be described bya Vanrsquot Hoff Arrhenius relationship

119863119894= 1198630exp (119864119863

119877119879

) (14)

Here 119863119894denotes the diffusion coefficient and 119863

0a preexpo-

nential factor and119864119863is the activation energy needed to create

and reach a void in the polymermatrixMeares [71] proposedthe following relation for the activation energy of diffusion

119864119863= 025 sdot 119873

0sdot 120587 sdot 119889

2sdot 120582 sdot CED mit CED =

119864coh119881119898

(15)

1198730is the Avogadro constant 119889 the kinetic diameter 120582

the horizontal separation CED the cohesive energy density119864coh the cohesive energy and 119881

119898the specific volume of

the polymer The preexponential factor 1198630in (14) can be

described for dense polymers in a first approximation usingthe Einstein-Smoluchowski relationship

1198630=

120582 sdot 120592th2

(16)

Here 120582 denotes the distance that it takes a diffusing com-ponent to reach the nearest empty space from a positionof equilibrium and 120592 is its mean thermal velocity Fromthe relations in (14) it is clear that the diffusion coefficientincreases with increasing temperature The relationships (15)and (16) illustrate the dependence of the diffusion coefficienton the molecular size and the voids in the polymer Thediffusion coefficient decreases with increasing molecularsize or increasing molecular weight So in glassy polymershigher activation energy is required to form an empty spaceas in elastomeric polymers For this reason the diffusioncoefficient is higher in the rubbery polymer and decreases insmaller steps with increasingmolecular weight Furthermorebecause of their small molecular weight small moleculesneed lower activation energy to reach the nearest empty spacethan larger molecules This explains why preferably smallmolecules are transported in dense glassy polymers

The diffusion of small molecules in the gas or vaporphase correlates with the fractional free volume (FFV) inthe polymer matrix This relationship is valid for materialcomponents with no or only a weak interaction with thepolymer chains (eg He N

2 H2 and CO

2) The FFV


model is an empirical model which postulates an exponentialrelationship between the diffusion coefficient and the FFV

119863119894= 119860119894exp(

119861119894

FFV)mit FFV =

119881119898minus 119881119894119900

119881119898

=

119881119898minus 13 sdot 119881

119882

119881119898

(17)

119860119894and 119861

119894are therein adjustable parameters that correlate

with the diameter volume and shape of the material compo-nents These parameters are not yet clearly defined becausedifferent units of measurement are used to describe thediameter and volume such as the kinetic Lennard-Jonesand Chung diameter and the critical volume and the vander Waals volume exist Both the cross-sectional area andthe length of the molecules affect the diffusion throughpolymeric membranes The FFV of a polymer is describedby its specific volume119881

119898(reciprocal density of the polymer)

by a constitutional repeating unit per mole at 0 K occupiedvolume 119881

1198940and the van der Waals volume of 119881

119882 The FFV is

thus the sumof the voids between the polymer chains A goodcorrelation between the diffusion coefficient and the FFV isonly observed with structurally related polymers limitingthe application of this model The distribution and size ofvoids in thick nonconductive polymer can be determined forexample using Positron Annihilation Lifetime Spectroscopy(PALS) [72 73] As it was already mentioned this modeldoes not take into account any interactions between the gasmolecules and the polymer chains There is a correlationbetween the dielectric constant 120576 of polymer membranes andthe FFV A connection with the diffusion coefficient is givenin the Clausius-Mossotti equation

119863119894= 119860lowast

119894exp(

minus119861lowast

119894

1 minus 119886

)mit 119886 = 13 sdot119881119882

119875119871119871

sdot

120576 minus 1

120576 + 2

(18)

Here 119860lowast119894and 119861

lowast

119894are adjustable parameters 119881

119882the specific

van der Waals volume and 119875119871119871

the molar polarization Theadditional consideration of the electrical interaction leadsto an improved correlation of the diffusion coefficient withstructurally related polymers

The second important parameter to describe the perme-ability and the release properties of dense polymer mem-branes is the sorption coefficient The sorption coefficient 119896

119894

can be calculated using (11) and (12)

119896119894=

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

=

119862119898

119894

119901119894

(19)

where 120593119894is the fugacity coefficient 120588

119894the density 120574

119894the

mean activity coefficient 1199010 the saturation pressure and 119872

the molecular weight The temperature dependence of thesorption coefficients can be described just as for the diffusioncoefficient using the Vanrsquot Hoff Arrhenius relationship

119896119894= 1198960exp(minus

Δ119867119878

119877119879

)mit Δ119867119878= Δ119867

119898+ Δ119867119888

Δ119866119898= Δ119867

119898minus 119879Δ119878

119898

(20)

Here 119896119894is the sorption coefficient of a material component in

a polymer 1198960is a preexponential factorΔ119867

119878is the adsorption

heat or adsorption enthalpy Δ119867119898is the enthalpy of mixing

Δ119867119888is the enthalpy of condensation Δ119866

119898is the free energy

of mixing and Δ119878119898is the entropy of mixing Substances are

mutually soluble when the free energy of mixing is negativeThe entropy of mixing is usually positive Therefore thesolubility depends on the value of the adsorption enthalpyΔ119867119898 The interaction of a dissolved component in a polymer

membrane may be described as follows

Δ119867119898= 119867119891119897+ 119867Pol minus 2 sdot 119867

119891119897-Pol (21)

Here 119867119891119897

is the enthalpy of the dissolved component 119867Polthe enthalpy of the polymermaterial and119867

119891119897-Pol the enthalpybetween the dissolved component and the polymer A corre-lation to the solubility parameters is given by

Δ119867119898= 119881 sdot (120575

119891119897minus 120575Pol)

2

sdot 120601119891119897sdot 120601Pol mit 120575

= (

119864coh119881

)

12

(22)

where 119881 is the total molar volume of solute and polymer sol-ubility 120575 are solubility parameters 120601 is the volume fractionand 119864coh is the cohesive energy In endothermic mixtures theadsorption enthalpy is always positive To obtain a negativefree energy of mixing Δ119867

119898lt 119879Δ119878

119898must be true and thus

the difference in the solubility parameters between materialcomponent and polymer must be minimal If 120575

119891119897asymp 120575Pol

Δ119867119898goes to zero and the material component is soluble in

the polymer material In case the solubility parameters of thematerial component and the polymer membrane are greatlydifferent the solid component is retained by the membraneThe retention capacity 119877

119894of a polymer membrane is defined

as

119877119894= (1 minus

119862119901

119894

119862119891

119894

) (23)

119862 denotes the concentration of a substance component 119894 inthe permeate (119901) and the feed (119891) The dimensionless termvaries between zero (no permeability) and 1 which is equal toa total permeability of a material component 119894 A relationshipbetween the equilibrium concentration 119862

119898

119894of a component

in the polymer phase and the sorption coefficient is givenaccording to Henryrsquos law by

119862119898

119894= 119896119894sdot 119901119894= 119870119867

119894sdot 119901119894 (24)

For ideal gases the sorption coefficient 119896119894is constant and

corresponds to theHenry constant119870119867119894of a component 119894This

linear assumption applies only to small concentrations and isobserved only in rubber-elastic polymers Upon interactionof a penetrant and polymer matrix a swelling can occur inrubbery polymers or polymers close to the glass transitionpoint (119879

119892) due to which the solubility increases When


polymers are close to119879119892 we call it plastificationThe solubility

isotherm then shows a progressive deviation from the linearbehavior and is described by the Flory-Huggins polymertheory In glassy polymermembranes the solubility isothermhowever shows a degressive behavior upon increasing partialpressure This behavior is described by the dual sorptionmodel which includes in addition to the linear Henrysorption surface adsorption according to the Langmuirrelationship

119862119894= 119862119867

119894+ 119862119871

119894= 119870119867

119894sdot 119901119894+

1198621198711015840

119894119887119901119894

1 + 119887119901119894

(25)

Here 119862119867119894is the Henry sorption 119862119871

119894the Langmuir sorption

119870119867

119894the Henry constant 119901

119894the partial pressure 119862119871

1015840

119894the

ldquohole saturationrdquo constant and 119887 the so-called hole-affinityconstant The solubility of many permanent gases in glassypolymers is described quite well by the dual sorption modelAnother important parameter to describe the separationproperties of dense polymer membranes is their selectivity

119878119875

119895119896=

119875119895

119875119896

= 119878119863

119895119896sdot 119878119896

119895119896 (26)

The selectivity 119878119901119895119896

is the ratio of the permeability of amaterialcomponent 119895 to a substance component 119896 if the materialcomponent 119895 is having the higher permeability throughthe membrane structure The selectivity is sometimes splitinto two terms The first term is the ratio of the diffusioncoefficients (119863) and the second term the ratio of the sorptioncoefficients (119896) of the material components 119895 and 119896 Thepermselectivity (separation factor) is another useful parame-ter for describing binary mixtures

120572119895119896

=

119883119901

119895

119883119891

119895

119883119891

119896

119883119901

119896

=

119883119901

119895sdot (1 minus 119883

119891

119895)

119883119891

119895sdot (1 minus 119883

119901

119895)

(27)

Here 119883 is the mole fraction of a material component 119895 and119896 in the permeate (119901) and the feed (119891) The separation factoris by definition always gt1 A relationship to the selectivity isgiven by

120572119895119896

= 119878119895119896

((119883119901

119895sdot 119901119901) 119901119891minus 119883119891

119895)

((119883119901

119896sdot 119901119901) 119901119891minus 119883119891

119896)

119883119891

119896

119883119891

119895

(28)

119878 refers to the selectivity of a binary mixture 119883 is the molefraction and 119901 is the partial pressure The superscripts referto the permeate (119901) and the feed (119891) and the subscripts tomaterial components119891 and 119896The separation factor is alwayssmaller than the selectivity If the partial pressure in the feedis much larger than in the permeate the separation factor isequal to the selectivity

lim119901119901119901119891rarr0

120572119895119896

= 119878119895119896 (29)

This can be concluded as follows the flux through a non-porous dense membrane depends on the diffusion andsorption of a material component The product of diffu-sion and sorption coefficients is called the permeabilitycoefficient (119875

119894) The diffusion coefficient 119863

119894correlates with

the molecular diameter of the material components andincreases with increasing molecular diameters The decreaseis in glassy polymers (119879 lt 119879

119892) more pronounced than

in the rubber-elastic polymers (119879 gt 119879119892) The diffusion

coefficient increases with temperature as with the temper-ature also the fractional free volume (FFV) increases inthe polymer The sorption coefficient 119896

119894of gases or vapors

rises with the boiling point and the critical temperatureof the adsorbed material components For gases above thecritical temperature the adsorption enthalpy Δ119867

119904is slightly

positive and is typically between 0 and 10 kJmolminus1 Thereforethe solubility increases only moderately with temperatureFor condensable gases Δ119867

119904is due to the high contribution

of the condensation enthalpy Δ119867119888negative (see (20)) and

the solubility decreases with increasing temperature Sorp-tion in glassy polymers thereby differs only slightly fromelastomeric polymers The dependence of the permeabilitycoefficient 119875

119894from the molecular diameter is comparatively

low in rubbery polymers and increases only slightly withincreasing diameter of the molecules In glassy polymers thepermeability coefficient generally decreases with increasingmolecular diameter In permanent gases the permeabilityincreases with temperature This can be explained in the waythat the diffusion depends a lot more on the temperature(activation energy for diffusion is between 20 and 80 kJmolminus1)than on the sorption (adsorption enthalpy is usually betweenminus10 and +10 kJmolminus1) In vapor molecules the condensationenthalpy Δ119867

119888is the dominating term For this reason the

permeability decreases for molecules in the vapor state withincreasing temperature [9 56 74ndash76] Important parametersto describe the release characteristics of the polymer are thusthe permeability just described (119875) and the retention capacity(119877) When considering binary mixtures often the selectivity(119878) or the separation factor (120572) for the characterization ofmembranes are used

23 MOX Sensor A MOX sensor changes its electricalresistance in contact with gases The operating principleof MOX sensors is based on the chemisorption of gasesin the presence of atmospheric oxygen The presence ofreducing and oxidizing gases leads to a change of the induceddepletion layer at the outer edge of the metal oxide grainsand thus to a change in the sensor resistance In all ourexperiments we used a tin oxide sensor with palladiumcatalyst (SnO

2Pd) which is an 119899-type semiconductor Upon

exposure to reducing gases such as H2 CO CH

4 ethanol

acetone and acetaldehyde excess electrons are emitted intothe conduction band of the SnO

2 This results in an increase

of the carrier concentration on the SnO2surface and the

resistance of the sensor is reduced Oxidizing gases such asNO2reduce the charge carrier concentration the Schottky

barrier is increased and the resistance of the sensor increasesThe sensor signal (119878) is used as relation between the signal at


equilibrium (1199090) and the signal in a changing gas composition

(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)

119877air denotes the resistance of the sensor in pure synthetic air(baseline) and upon reactionwith gas changing the resistanceto 119877gas In order to obtain positive values the relation of thesensor signal (119878red 119878ox) must be reciprocal for reducing andoxidizing gases The sensor signal is always ge1 If the signal iscong1 no change in resistance takes place The sensor signal nowcorresponds per definition to the permeability (119875)

In addition to the permeability the retention capacityis another important parameter to describe the separationproperties of polymers The retention capacity (119877) is definedas the normalized ratio of the concentration of a solidcomponent (119894) in the permeate (119901) to the concentration inthe feed (119891) The sensor signals are proportional to the trueconcentration This requires an adaptation of (23)

119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)

where 119888 is the concentration 119878 is the sensor signal of MOXsensors from (30) the subscript 119894 refers to a material compo-nent and the superscript 119901 or 119891 refers to the permeate andfeed Since the SnO

2Pd sensors have a high reproducibility

between 89 and 94 two different sensors can be used tomeasure the concentration in the feed and permeate Thereproducibility (119876) is defined as

1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)

where 119899 is number of sensors 1199091015840119896is signal of sensor 119896 and

1199091015840

max is signal maximum of all sensorsIn the case of 119876 = 0 the sensors are mutually not

reproducible in the case of 119876 asymp 100 the signals are identical[77]

If now the retention capacity reaches a value of 1 themembrane is completely permeable for a material com-ponent If the retention capacity is zero then a materialcomponent can diffuse freely through the membrane

3 Experimental Setup

As mentioned in the introduction for many applicationfields of gas sensors there is a great interest in membraneswith high selectivity and permeability having at the sametime the smallest possible diameter Typically gas sensors

are mounted on TO-39 sockets The metal or plastic capsthat are glued onto the socket to protect the sensors usuallyhave an outer diameter of about 8mm For easy integrationthe diameter of the membranes must not exceed 64mmThe membranes we used are symmetrical dense polymermembranes without support layer with thicknesses between8 120583m (PI) and 50120583m (PMP) In order to prevent damage ordeformation of the thin membrane during installation theyare fixed on polymer supportsThis is shown schematically inFigure 3(a) A stainless steel plate (A) with an outer diameterof 12mm and a height of 16mm is the basis for applying anonoutgassing two-component epoxy adhesive at the edge(H70E-4 Company EPO TEK Inc) (B) The inner diameterof the stainless steel plate is 64mm

The membrane is punched out placed on the stainlesssteel plate and lightly pressed with a pair of tweezers so thatthe adhesive runs under the membrane Then another layerof glue is applied at the edge (C) In the last step a secondstainless steel plate is placed on top and pressed on andafterwards the adhesive cured for two hours at a temperatureof 80∘C (D) The stainless steel plate directed towards themembrane side is trimmed and polished The photo on theright shows an assembled carrier with membranes of polyte-trafluoroethylene (PTFE) polyetheretherketone (PEEK) andpolyimide (PI)

The experimental setup consists of two chambers con-nected in series The chambers are interconnected by meansof Swagelok Chamber A is made of Teflon (PTFE) Thechamber is used to measure the concentration humidity andtemperature in the feed The chamber can be equipped withup to six sensors mounted on TO-39 sockets The sensorscomprise MOX gas sensors (SnO

2Pd) and temperature and

humidity sensors (HYT221) from IST AG Switzerland Ametal cap is glued onto a printed circuit board (PCB) whichis just the same as the caps on the HYT221 and the gassensorsThe housing of the sensor is integrated into the PTFEchamber Chamber B is used to measure the concentration ofthe permeate Six stainless steel fittings from Serto (SO 51194-8-14) with an inner diameter of 8mm are screwed into themeasuring chamber made of aluminumThe tightness of thesetup is crucial for the examination of the membranes Forthis purpose the TO-39 sockets with the gas sensors (not theHYT221) are soldered to the fitting The membrane supportsare interchangeable and can be screwed to the fitting Thevolume of gas below the diaphragm is 151 cm3 The tightnessof the part at themembrane is ensured by the use of two PTFEsealing disks above and below the carrier as well as a furtherethylene propylene diene monomer (EPDM) rubber sealingring The thread is additionally sealed with PTFE tape Theschematic structure is illustrated in Figure 4

The tightness of the structure (polymeric carrier stainlesssteel fittings seals etc) was examined by carriers that havebeen built with 100 120583m thick gas-tight aluminum foil In atest 1000 ppmH

2was applied over a period of 20 minutes

The SnO2Pd sensors would show already at a very low

concentration of 1 ppmH2sensor signals in the order of 7 so

that even smallest leaks in the system could be noticed In thetest no leak was observed


(A)

(B)

(C)

(D)

Stainless steel disc

Epoxy resin adhesive

Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)

Figure 3 (a) Construction of polymer support (A) stainless steel plates with an inner diameter of 64mm an outer diameter of 12mm anda height of 16mm are used as substrates (B) addition of a two-component epoxy adhesive (EPO-TEK H70E Company Epoxy TechnologyInc) (C) placing of the polymer membrane (D) pressing of a second stainless steel plate and curing of the adhesive for two hours at 80∘C(b) Photo of polymeric carriers with membranes of PI PTFE and PEEK

Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support

Stainless steel fitting

Figure 4 Experimental setup for investigating the separation properties of polymer membranes In chamber A any six sensors that aremounted on TO-39 sockets can be integrated The sensors are used to measure the gas concentration humidity and temperature in the feedIn chamber B six interchangeable stainless steel fittings are integrated The sensors are soldered into the fitting The polymer supports arescrewed with EPDM and PTFE seals into the fitting

In a second test the sensor signals of SnO2Pd sen-

sors in chamber A were compared with those of chamberB (without polymer carrier) during 20-minute exposureto H2(150 ppm) CO (30 ppm) CH

4(1000 ppm) ethanol

(500 ppm) acetone (500 ppm) and acetaldehyde (25 ppm)and additionally to different humidity levels The sensorsignals in chamber A and chamber B show a very good agree-ment and can therefore be used to calculate the retentioncapacity

4 Results

41 Polyolefins From the group of polyolefins the semicrys-talline homopolymers of polyethylene with high density(HDPE) low density (LDPE) graphite filling (PE + graphite)polypropylene (PP) and poly-4-methylpentene-1 (PMP)were tested for their separation properties In Figure 5 thefeed and permeate signals upon exposure to 150 ppmH

2

30 ppmCO 1000 ppmCH4 500 ppm ethanol 500 ppm ace-

tone and 25 ppm acetaldehyde are shown For illustration

the cross-links in HDPE and LDPE are also shown schemat-ically

For the LDPE membrane we obtained high signalchanges for H

2 ethanol and acetone and small signal

changes for CH4and acetaldehyde Only CO was completely

retained by the LDPE membrane In the HDPE membrane70ndash80 of the macromolecules are in orthorhombic crys-talline form that is in a highly ordered state with the greatestpacking density (crystal lamellae) In this condition the inter-molecular partial valence forces act optimally Interestinglythis leads to increased permeability for H

2 ethanol acetone

acetaldehyde and CH4 This can be explained with the fact

that due to a decrease in entanglement (amorphous regions)compared to LDPE the mobility of the chains and thus thediffusion is facilitated by the membrane matrix The graphitefilling in PE + graphite causes an increase in the densityand thus a reduction of the free volume This increases theretention capacity and the membrane is permeable only tothe gases acetone and ethanol


Table 2 Permeate signals of theMOX sensor using LDPEHDPE PE+ graphite PP and PMPmembranesThe values given are the arithmeticmean of three measurements

Membrane Sensor H2

CO CH4

Ethanol Acetone AcetaldLDPE MOX 21 mdash mdash 325 219 mdashHDPE MOX 27 mdash mdash 809 709 13PE + graphite MOX mdash mdash mdash 15 17 mdashPP MOX 23 mdash mdash 44 32 mdashPMP MOX 58 mdash 11 296 132 11

R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de

FeedPermeate PE-LD membranePermeate PE-HD membranePermeate PE + graphite membrane

MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)

Figure 5 (a) Separation properties of LDPE HDPE and PE + graphite upon exposure to 150 ppmH2 30 ppm CO 1000 ppm CH

4 500 ppm

ethanol 500 ppm acetone and 25 ppm acetaldehyde The diameter of the membranes is 64mm (b) structure of the PE monomer and cross-linking of the macromolecules in HDPE and LDPE

The MOX signals using the HDPE PP and PMP mem-branes are shown in Figure 6 For the PP membrane thesensor signals are sim20x lower in comparison with the HDPEmembrane when exposed to ethanol and acetone In contrastthe sensor signal change in response to H

2is only minimal

Due to the methylene side group and the resulting lowerdensity (low density is synonymous with large interatomicdistances) one would rather expect an increase in signals

In contrast to LDPE in which a decreased sensor signalcan be assigned to entanglement in amorphous regions thiscannot be the reason in PP because this has a similar degree ofcrystallinity compared to HDPE It can therefore be assumedthat the increased retention capacity is associated with the 3

1

helices which PP is formingThe assumption is reinforced bythe fact that even when using the PMPmembrane lower feedsignals are obtained for ethanol and acetone Due to differentlinear thermal expansion coefficients PMP tends to build upcavities between the amorphous and crystalline regions andthe sensor signal increases for hydrogen and is even morepronounced for CH

4and acetaldehydeThe permeate signals

of the examined polyolefins are summarized in Table 2

Involving the feed signals we obtain the results summa-rized in Table 3 for the retention capacities of the differentpolymers If the adjacent gas phase and the polymer areboth nonpolar this should lead to a substantial increasein the adsorption of the adjacent phase and an associatedincrease in the diffusion The investigated polyolefins are allnonpolar but exhibit a high permeability for the polar gasethanol (169 Debye) and acetone (288 Debye) while thenonpolar methane and the weakly polar CO (011 Debye)are completely held back In the case of the polyolefinsa relatively high retention capacity with respect to thenonpolar H

2is observed The thermoplastics show both a

permeability to nonpolar and polar gases and are thereforelittle selective with the exception of HDPE In the HDPEmembrane the retention capacity is for acetone at 0305which is significantly lower than the retention capacity forethanol acetaldehyde CO H

2 and methane Thus it shows

an increased selectivity to acetoneIn these nonpolar polyolefins the macromolecules are

held together only by weak dispersion forcesThese forces aremost pronounced in the highly ordered crystalline domains


Table 3 Retention capacities of the polyolefins LDPE HDPE PE + graphite PP and PMPThe values given are the arithmetic mean of threemeasurements

Membrane Sensor H2

CO CH4

Ethanol Acetone AcetaldPE-LD MOX 0993 mdash mdash 0852 0796 mdashPE-HD MOX 0988 mdash mdash 0619 0305 099PE + C MOX mdash mdash mdash 0997 0993 mdashPP MOX 0992 mdash mdash 0983 0978 mdashPMP MOX 0969 mdash 0995 0874 0887 0995

R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de

FeedPermeate HDPE membranePermeate PP membranePermeate PMP membrane

MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)

Figure 6 Separation properties ofHDPE PP andPMPupon exposure to 150 ppmH2 30 ppmCO 1000 ppmCH

4 500 ppmethanol 500 ppm

acetone and 25 ppm acetaldehyde The diameter of the membranes is 64mm

The degree of crystallization of the membrane increases inthe order LDPE lt PMP lt PP lt HDPE Interestingly HDPEwhich consists of largely linear macromolecules having alow degree of branching (ie high degree of crystallization)has the lowest retention capacity Through the introductionof side chains the interatomic distances between adjacentmacromolecules increase This leads to a decrease in densityThe density of the membrane thus decreases in the orderof PE + graphite gt HDPE gt LDPE gt PP gt PMP Themeasurements have shown that with decreasing density theretention capacity of themembrane increases contrary to ourexpectationsWe assume that this effect is related to the chainstructure since the macromolecules in PP and PMP form 3

1

helices in contrast to the PE typesWe now look at the permeation of water vapor For this

purpose the absolute humidity was increased in two steps of48 gm3 and held for two hours The concentrations in thefeed and permeate is plotted in Figure 7

The permeability to water vapor is very low in all exam-ined polyolefins (cf Table 4) So the absolute humidity risesin the permeate during the two-step profile to a maximum of17 gm3 in PMP or 14 gm3 in LDPE

LDPE is a widely branched homopolymer with short-and long-chain branches and thus has an enlarged moleculedistance compared to other PE types (eg LDPE or PE +graphite) PMP is a largely isotactic thermoplastic The bulkyside group leads to an abnormally low density of 083 gcm3PMP is partially crystalline with a degree of crystallization of65 At room temperature the amorphous domains are quitedense Due to the different coefficients of thermal expansioncavities are forming between the amorphous and crystallineareasThis explains the increased permeability to water vaporin comparison to PP HDPE and PE + graphite The waterabsorption is still less than 001

42 Thermoplastic Polycondensates The second class of sub-stances which is analyzed with respect to their separa-tion properties are thermoplastic polycondensates Herethe membranes are made of polycarbonate (PC) polyetherether ketone (PEEK) polyether sulfone (PES) polyethy-lene terephthalate (PET) polyethylene naphthalate (PEN)polyamide (PA6) polyimide (PI) and polyetherimide (PEI)Of particular importance in this class of substances are withthe exception of PA6 the aromatic ring compounds that


Table 4 Changes in the absolute humidity in the permeate when using polyolefin membranes made of LDPE HDPE PE + graphite PP andPMP The concentrations in the feed and permeate are measured with a digital 119879RH sensor (HYT221)

Membran Sensor Δ119860Feed [gm3] Δ119861Feed [gm

3] Δ119860Permeat [gm3] Δ119861Permeat [gm

3]PE-LD HYT221 48 94 07 14PE-HD HYT221 49 96 02 05PE + C HYT221 51 10 0 02PP HYT221 48 95 02 02PMP HYT221 48 98 08 17

t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)

FeedPermeate PE-HD membranePermeate PP membranePermeate PMP membrane

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)

Figure 7 (a) Water vapor permeability of LDPE HDPE and PE + graphite membranes (b) Water vapor permeability of the polyolefinsHDPE PP and PMP The absolute humidity is increased in two steps of 48 gm3 (Δ119860 Δ119861)

is heterocyclic compounds contained in the backbone Incontrast to the flexible and mobile -CH

2groups they lead

to a stiffening of the chain links A linear combination ofaromatics via an ether (-O-) ketone (-CO-) sulfone (-SO

2-)

aryl- or ether imide group leads to a strong increase of bothchemical resistance and temperature resistance The linkingof the aromatics via an ester (-CO-O-) or a carbonate group(-O-CO-O-) however leads to a decrease of the temperatureresistance The continuous operating temperatures are stillabove those of the polyolefins In contrast to the alreadyinvestigated polymers from the class of polyolefins thesepolymers should have a lower permeability due to theirhigher strength and stiffnessThis should also lead to a higherselectivity The majority of the selected polymers are alsoamorphous (PC PEEK PEN PI PEI and PES) In contrastthe polyolefins have degrees of crystallization in the rangebetween 20 and 80 In the examined polyolefins themonomers consist exclusively of carbon (C) and hydrogen(H) The investigation of the separation properties of thesemembranes has shown a high retention capacity comparedto nonpolar gases and water vapor We therefore supposethat by a slight polarization of the polymer for example viathe inductive effect of an ether group (-O-) the selectivity

can be increased to nonpolar gases The polymers PEEKPES PET PEN PI and PEI contain these ether groups inthe backbone Through further linkages of aromatics withketone (-CO-) ester (-CO-O-) or carbonate groups (-O-CO-O-) it is possible to study the effect of these additionallinks on the separation properties Figure 8 shows the feedand permeate signals using a PC PEEK and PES membraneIn all membranes permeability to H

2can be observed For

the PC membrane we additionally observed a signal whenexposed to 30 ppmCO However the sensor signal is verylow at 104 The dimethyl group in PC leads to an increasein the distances between adjacent macromolecules The PChas a lower density than PEEK and PES It can therefore beassumed that the increased distances in combination withthe weak polar carbonate group favor the permeability forCO Concerning their permeability for H

2 the sensor signals

increase in the order of PES lt PC lt PEEKThus the highly polar sulfone groups (-SO

2-) in PES

result in an increase of the retention capacity compared toH2 while the angled carbonate groups (-O-CO-O-) in PC

and the alternating ether (-O-) and ketone (-CO-) groups inPEEK favor permeability toH

2Wenow consider the feed and

permeate signals of PET and PEN membranes in Figure 9


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

deFeedPermeate PC membranePermeate PEEK membranePermeate PES membrane

MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)

Figure 8 Separation properties of PC PEEK and PES upon exposure to 150 ppmH2 30 ppmCO 1000 ppmCH

4 500 ppm ethanol 500 ppm


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de

FeedPermeate PET membranePermeate PEN membrane

MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)

Figure 9 Separation properties of PET and PEN upon exposure to 150 ppm H2 30 ppm CO 1000 ppm CH



The structure of these macromolecules allows much higherchain flexibility due to the flexible CH

2groups Unlike PC

PEEK and PES PET and PEN contain ester groups (-CO-O-)in the backbone In ester groups carboxyl oxygen is bondeddirectly to the carbonyl groupThis results in a delocalizationof the charge of the carboxyl oxygen towards the electron-withdrawing carbonyl oxygen So the polarization is lowerthan that of a ketone group but higher than that of an ethergroup Because ester groups are present only in PET and PENas a component of the macromolecules these membranes are

more polar than membranes made of PC PEEK and PESThrough their relatively long chains between the aromaticgroups membranes of PET and PEN have a higher densitythanmembranes of PC and PEEK and thus lower interatomicdistances This explains the low gas permeability of thesemembranes compared to the already examined PC PEEKand PES

In addition to the already discussed PES membranefrom the group consisting of polyarylsulfones the separationproperties of nitrogen-thermoplastics in which aliphatic or

Journal of Sensors 17R

(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de

FeedPermeate PA6 membranePermeate PI membranePermeate PEI membrane

MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)

Figure 10 Separation properties of PA6 PI and PEI upon exposure to 150 ppm H2 30 ppm CO 1000 ppm CH



cycloaliphatic or aromatic chain links are disrupted by amide(PA6) or imide groups (PI PEI) were examinedmore closelyThe feed and the permeate signals of these membranes areplotted in Figure 10 Aliphatic polyamides are constructedfrom methylene- (-CH

2-) and amide groups (-CO-NH-)

This causes two types of partial valency forces betweenthe macromolecules These are dispersion forces betweenthe methylene groups and hydrogen bridge bonds betweenthe amide groups The properties of PA are very stronglyinfluenced by the ratio of methylene and amide groups Withan increasing number of methylene groups the polarity thedensity and the melting point of the polyamides decreaseThe number of methylene groups in the PA6membrane usedis five Due to the small number of methylene groups and thedifference between the electronegativity of the NH bond of09 and the C = 0 bond of 10 PA6 is strongly polar Therebythe membrane shows for acetaldehyde a very high reten-tion capacity for 150 ppmH

2 30 ppmCO 1000 ppmCH

4

500 ppm ethanol 500 ppm acetone and 25 ppm acetalde-hyde Since this thermoplastic contains only ketone-groupsour assumption that the permeability for nonpolar gases isfavored in polymers containing ether groups is verified again

Also the thermoplastics PI and PEI are considerably polardue to the electron-withdrawing of the two carbonyl groups(-M effect) The monomers of these membranes containunlike PA6 one (in PI) or two (in PEI) ether groupsConsidering the permeate signals of these membrane uponexposure with 150 ppm H

2we see that with increasing

number of ether groups the permeability for H2increases

while the gases CO CH4 ethanol acetone and acetaldehyde

are completely retainedThe sensor signal of theMOX sensoris 15 for the PEI membrane which is slightly above the signalobtained with the PEEK membrane The monomers of thePEEK membrane contain two ether groups just as the PEIThe slightly increased permeability of the PEI membrane forH2is explained by the increased distances between adjacent

macromolecules by the dimethyl group The feed signals ofthe tested thermoplastic polycondensates are summarized inTable 5

The retention capacities of the membranes determinedwith the aid of the MOX sensor are summarized in theTable 6 Since for the PET PEN and PA6 membranes nosignals were observed in the feed they are not listed in thetable Table 7 gives the change of the absolute humidity in thepermeate for the thermoplastic polycondensates PC PEEKPES PET PEN PA6 PI and PEI

The thermoplastic polycondensates were further inves-tigated with increased concentrations of the gases CO(100 ppm) and CH

4(3000 ppm) as well as the nonpolar

gases NO2(1 ppm) and CO

2(1 vol) Figure 11 shows the

results of the measurement An increase of the concentrationis equal to an increase in the area or a reduction of thefilm thickness In PET PEN and PA6 showing very highbarrier properties when exposed to 150 ppm H

2 30 ppm

CO 1000 ppm CH4 500 ppm ethanol 500 ppm acetone

and 25 ppm acetaldehyde increased concentrations do not


Table 5 Permeate signals of the MOX sensor using PC PEEK PES PET PEN PA6 PI and PEI membranes The values given are thearithmetic mean of three measurements

Membrane Sensor H2

CO CH4

Ethanol Acetone AcetaldPC MOX 13 104 mdash mdash mdash mdashPEEK MOX 14 mdash mdash mdash mdash mdashPES MOX 12 mdash mdash mdash mdash mdashPET MOX mdash mdash mdash mdash mdash mdashPEN MOX mdash mdash mdash mdash mdash mdashPA6 MOX mdash mdash mdash mdash mdash mdashPI MOX 11 mdash mdash mdash mdash mdashPEI MOX 15 mdash mdash mdash mdash mdash

Table 6 Retention capacity of the investigated thermoplastic polycondensates PC PEEK PES PI and PEIThe values given are the arithmeticmean of three measurements

Membrane Sensor H2

CO CH4

Ethanol Acetone AcetaldPC MOX 0998 0995 mdash mdash mdash mdashPEEK MOX 0997 mdash mdash mdash mdash mdashPES MOX 09991 mdash mdash mdash mdash mdashPI MOX 09997 mdash mdash mdash mdash mdashPEI MOX 0996 mdash mdash mdash mdash mdash

Table 7 Change of the absolute humidity in the permeate for the thermoplastic polycondensates PC PEEK PES PET PEN PA6 PI andPEI The concentrations in the feed and permeate were measured with a digital 119879RH sensor (HYT221)

Membrane Sensor Δ119860Feed [gm3] Δ119861Feed [gm


3]PC HYT221 5 96 22 42PEEK HYT221 46 9 11 22PES HYT221 45 9 31 6PET HYT221 53 101 09 18PEN HYT221 48 97 01 02PA6 HYT221 46 91 11 34PI HYT221 46 91 13 26PEI HYT221 46 9 13 27

cause any higher permeate signals In contrast minimalsignals were observed for 3000 ppm CH

4in the H

2-selective

membranes PC PEEK PES PI and PEIThe highest permeability to CH

4showed the PEEK and

PEI membranes Thus these membranes are modified (layerthickness area) a high selectivity towards CH

4can be

achieved (in the absence ofH2) To investigate the permeation

of water vapor the absolute humidity was increased in twosteps of 48 gm3 just as for the polyolefins andmeasured fortwo hours eachThemeasured concentrations in the feed andpermeate are plotted in Figure 12

With the exception of PEN the permeability to watervapor in all thermoplastic polycondensates is higher than thepermeability of polyolefins It is striking that the amorphousthermoplastics PC PI PEI and PES have a significantlyhigher permeability to water vapor than the examined ther-moplastics PET PEN and PEEK with partially crystallineregions An exception is the AB-polyamide PA6 With27M it has the highest water absorption of all investigatedthermoplastics

The number of -CH2groups between the recurring

carbonamide groups in PA6 is five In the linear PA6macromolecules only every second functional group allows ahydrogen bondThis leads to increased water absorption Butinterestingly the PA6 shows no permeability when exposed tothe gases H

2 CO CH

4 ethanol acetone acetaldehyde NO

2

and CO2

5 Summary and Outlook

Our results can thus be summarized as follows In theexamined nonpolar polyolefins the macromolecules are heldtogether only by weak dispersion forces The strength of thebond is about 1500 to 11000 of a primary valency bondTherefore the separation characteristics are primarily basedon the arrangement and cross-linking of themacromoleculesDispersion forces are most pronounced in the highly orderedcrystalline domains The degree of crystallization of themembrane increases in the order LDPEltPMPltPPltHDPEThe degree of crystallization influences the permeability and


R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250

FeedPermeate PC membranePermeate PEEK membranePermeate PES membrane

MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250

FeedPermeate PI membranePermeate PEI membrane

MOS (SnO2Pd)

(b)

Figure 11 Separation characteristics of the membranes PC PEEK and PES (a) and PI and PEI (b) during the exposure to an increasedconcentration of CO (100 ppm) and CH

4(3000 ppm) and 1 ppm NO

2and 1 vol CO

2 The diameter of the membranes is 64mm

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

FeedPermeate PC membranePermeate PET membranePermeate PEN membranePermeate PEEK membrane

(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

FeedPermeate PA6 membranePermeate PI membranePermeate PEI membranePermeate PES membrane

(b)

Figure 12 (a) Water vapor permeability of PC PET PEN and PEEK membranes (b) Water vapor permeability of PA6 PI PEI and PESmembranes The absolute humidity is increased in two steps of 48 gm3 (Δ119860 Δ119861)

selectivity of a polymer membrane Increasing degree ofcrystallinity (increasing density) increases selectivity whilethe permeability or solubility decreases with the increaseof the crystalline domains However this is not valid ingeneral since certain polymers have a specific permeabilityto chemically similar construction gases or vapors Throughthe introduction of side chains the interatomic distancesbetween adjacent macromolecules are larger This leads to

a decrease in density The density of the membrane thusdecreases in the order of PE + graphite gt HDPE gt LDPEgt PP gt PMP A low density is synonymous with largeratomic distances This results in higher gas permeability Themeasurements have shown that with decreasing density theretention capacity of the membrane increases contrary toexpectations We assume that this effect is related to thechain structure since the macromolecules in PP and PMP


form 31helices in contrast to the PE-types The investigated

polyolefins both show permeability to nonpolar and polargases and are not very selective with the exception ofHDPE In principle the nonpolar polyolefins would havehigher permeability to nonpolar material components Thiswas not observed in our study In the HDPE membranethe retention capacity for ethanol acetaldehyde CO H

2

and CH4is significantly higher than that for acetone Thus

high acetone selectivity can be achieved by a modification(increase in layer thickness or reduction of the area) ofthis membrane The class of polyolefins includes not onlynonpolar polymers but also a variety of polar polymers Theinvestigation of the separation properties of LDPE HDPEPE + graphite PP and PMP has revealed an increased reten-tion of nonpolar gases and water vaporWe therefore supposethat in a slightly polarized membrane (inductive effect) thetransmittance for nonpolar gases is increased Interestingmaterials for further studies would be for example polyvinylchloride (PVC) ethylenevinyl acetate copolymers (EVAC)ethylenevinyl alcohol copolymers (EVOH) ethyleneethylacrylate copolymers (EEAK) or polyoxymethylene (POM)and polymethyl methacrylate (PMMA) from the substancegroup of polyacrylates or polyacetals Another possibility is tochemically further modify PE Firstly PE can be cross-linkedvia high-energy 120573- or 120574-radiation peroxide or azo or silanecross-linking (PE-X) Secondly the surface can be chemicallymodified by chlorinating with radical formers (PE-C) or cor-rosive gases such as fluorine (F

2) or sulfur trioxide (SO

3) [61]

The membranes PC PEEK PES PI and PEI are highlyselective to H

2The gases CO ethanol acetone acetaldehyde

NO2 andCO

2were completely retained by themembranes at

the specified concentrations The presence of ether groups inthe backbone facilitates the permeability of H

2 The highest

permeate signals were obtained using the PEEK and PEImembrane Thus when exposed to H

2 the height of the

sensor signals correlates with the number of ether groupsUpon exposure with an increased methane concentrationof 3000 ppm a slight transmittance is observed in themembranes of PC PEEK PES PI and PEI The highest per-meabilities showed themembranesmade of PEEK and PEI Areduction of the layer thickness or an enlargement of the areashould lead to a high selectivity towards CH

4in the absence

of H2 The measurements have shown that even highly polar

polymers with sufficient nonpolar areas in the backbone arevery selective towards nonpolar gases With the exception ofPEN the permeability to water vapor is in all investigatedthermoplastic polycondensates higher than in polyolefins Itis striking that the amorphous thermoplastics PC PI PEIand PES have a significantly higher permeability to watervapor than the examined thermoplastics PET PEN andPEEK with partially crystalline regions Amorphous poly-mers have a larger number of cavities and thus an enlargedpermeability in comparison to semicrystalline polymers Anexception is the aliphatic PA6 With its small number ofmethylene groups this membrane shows very high barrierproperties against the gases H

2 CO CH

4 ethanol acetone

acetaldehyde NO2 and CO

2but has interestingly enough

very high water vapor permeabilityWith an increasing num-ber of methylene groups the gas permeability of aliphatic

polyamides should rise Other interesting membranes wouldthus be the polyamides PA11 PA12 PA610 and PA612Since the permeability for nonpolar gases is promoted byether groups for example polyphenylene ether (PPE) andpolyphenylene oxide (PPO) should have good separationproperties

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] P GrundlerChemische Sensoren Eine Einfuhrung fur Naturwis-senschaftler und Ingenieure Springer Berlin Germany 2004

[2] P Hauptmann Sensoren Prinzipien und Anwendungen HanserPublishers Munich Germany 1990

[3] E Hering and G Schonfelder Sensoren in Wissenschaft undTechnik Funktionsweise und Einsatzgebiete Vieweg+TeubnerWiesbaden Germany 2012

[4] C O Park and S A Akbar ldquoCeramics for chemical sensingrdquoJournal of Materials Science vol 38 no 23 pp 4611ndash4637 2003

[5] S Akbar P Dutta and C Lee ldquoHigh-temperature ceramicgas sensors a reviewrdquo International Journal of Applied CeramicTechnology vol 3 no 4 pp 302ndash311 2006

[6] C Pijolat J P Viricelle G Tournier and P MontmeatldquoApplication of membranes and filtering films for gas sensorsimprovementsrdquoThin Solid Films vol 490 no 1 pp 7ndash16 2005

[7] N B McKeown and P M Budd ldquoPolymers of intrinsic micro-porosityrdquo in Encyclopedia of Membrane Science and TechnologyE M V Hoek and V V Tarabara Eds vol 2 pp 781ndash797 JohnWiley amp Sons Hoboken NJ USA 2013

[8] M Barboiu ldquoConstitutional dynameric networks for mem-branesrdquo in Ecyclopedia of Membrane Science and Technology EM V Hoek and V V Tarabara Eds vol 2 pp 945ndash963 JohnWiley amp Sons Hoboken NJ USA 2013

[9] E Favre ldquoPolymericmembranes for gas separationrdquo inCompre-hensive Membrane Science and Engineering Membrane Opera-tions inMolecular Separations E Drioli and L Giorno Eds vol2 pp 155ndash212 Elsevier Kidlington UK 2010

[10] H Buschatz B Dageforde K Jakoby K-V Peinemann and DPaul ldquoHochselektive stofftrennungen mit carriermembranenmdashstand der entwicklung und erwartungenrdquo Chemie IngenieurTechnik vol 73 no 4 pp 297ndash303 2001

[11] A Raza and B Ding ldquoSuperhydrophobic biomimetic fibrousmembranesrdquo in Encyclopedia ofMembrane Science and Technol-ogy E M V Hoek and V V Tarabara Eds vol 2 pp 984ndash1021John Wiley amp Sons Hoboken NJ USA 2013

[12] MUlbricht lsquolsquoOberflachenmodifikationrdquo inMembranen Grund-lagen Verfahren und Industrielle Anwendungen K OhlroggeandK Ebert Eds chapter 3 pp 47ndash75Wiley-VCHWeinheimGermany 2006

[13] Y Fang Z-K Xu and J Wu ldquoSurface modification of mem-branesrdquo in Encyclopedia of Membrane Science and TechnologyE M V Hoek and V V Tarabara Eds vol 1 pp 460ndash474 JohnWiley amp Sons Hoboken NJ USA 2013

[14] S Ramakrishna ZMa and TMatsuura Polymermembranes inBiotechnology Preparation Functionalization and Applicationedited by S Ramakrishna Z Ma T Matsuura chapter 3-4Imperial College Press London UK 2011


[15] H B Park ldquoGas separation membranesrdquo in Encyclopedia ofMembrane Science and Technology E M V Hoek and V VTarabara Eds vol 1 pp 139ndash171 JohnWiley amp Sons HobokenNJ USA 2013

[16] B T Low YWang and T-S Chung ldquoPolymericmembranes forenergy applicationsrdquo in Encyclopedia of Membrane Science andTechnology E M V Hoek and V V Tarabara Eds vol 3 pp2066ndash2102 John Wiley amp Sons Hoboken Nj USA 2066

[17] R Rego N Caetano and A Mendes ldquoHydrogenmethaneand hydrogennitrogen sensor based on the permselectivity ofpolymeric membranesrdquo Sensors and Actuators B Chemical vol111-112 pp 150ndash159 2005

[18] S Kitsukawa H Nakagawa K Fukuda S Asakura S Taka-hashi andT Shigemori ldquoInterference elimination for gas sensorby catalyst filtersrdquo Sensors andActuators B Chemical vol 65 no1ndash3 pp 120ndash121 2000

[19] P Althainz A Dahlke M Frietsch-Klarhof J Goschnick andH J Ache ldquoReception tuning of gas-sensor microsystems byselective coatingsrdquo Sensors and Actuators B Chemical vol 25no 1ndash3 pp 366ndash369 1995

[20] M Fleischer S Kornely T Weh J Frank and H MeixnerldquoSelective gas detection with high-temperature operated metaloxides using catalytic filtersrdquo Sensors andActuators B Chemicalvol 69 no 1 pp 205ndash210 2000

[21] TWehM Fleischer andHMeixner ldquoOptimization of physicalfiltering for selective high temperature H

2sensorsrdquo Sensors and

Actuators B Chemical vol 68 no 1ndash3 pp 146ndash150 2000[22] A Cabot J Arbiol A Cornet J R Morante F Chen and

M Liu ldquoMesoporous catalytic filters for semiconductor gassensorsrdquoThin Solid Films vol 436 no 1 pp 64ndash69 2003

[23] C H Kwon D H Yun H-K Hong et al ldquoMulti-layered thick-film gas sensor array for selective sensing by catalytic filteringtechnologyrdquo Sensors and Actuators B Chemical vol 65 no 1ndash3pp 327ndash330 2000

[24] M Vilaseca J Coronas A Cirera A Cornet J R Morante andJ Santamarıa ldquoUse of zeolite films to improve the selectivity ofreactive gas sensorsrdquo Catalysis Today vol 82 no 1ndash4 pp 179ndash185 2003

[25] G Hagen A Dubbe F Rettig et al ldquoSelective impedancebased gas sensors for hydrocarbons using ZSM-5 zeolite filmswith chromium(III)oxide interfacerdquo Sensors and Actuators BChemical vol 119 no 2 pp 441ndash448 2006

[26] O Hugon M Sauvan P Benech C Pijolat and F LefebvreldquoGas separation with a zeolite filter application to the selectivityenhancement of chemical sensorsrdquo Sensors and Actuators BChemical vol 67 no 3 pp 235ndash243 2000

[27] K Sahner D Schonauer P Kuchinke and R Moos ldquoZeolitecover layer for selectivity enhancement of p-type semiconduct-ing hydrocarbon sensorsrdquo Sensors and Actuators B Chemicalvol 133 no 2 pp 502ndash508 2008

[28] A Afonja S Dungey R Binions I Parkin D Lewis andD Williams ldquoGas sensing properties of composite tungstentrioxide-zeolite thick filmsrdquo ECS Transactions vol 16 no 24pp 77ndash84 2009

[29] R Binions H Daviesa A Afonja and et al ldquoZeolite modifieddiscriminating gas sensorsrdquo Journal of The ElectrochemicalSociety vol 156 no 3 pp J46ndashJ51 2009

[30] R Binions A Afonja S Dungey D Lewis I Parkin and D EWilliams ldquoZeolite modification Towards discriminating metaloxide gas sensorsrdquo ECS Transactions vol 19 no 6 pp 241ndash2502008

[31] M Hubner A Yuece G C Mondragon Rodrıguez B SaruhanN Barsan and U Weimar ldquoBaTi

095Rh005

O3catalytic filter

layermdasha promising candidate for the selective detection of COin the presence of H

2rdquo Procedia Engineering vol 5 pp 107ndash110

2010[32] S Ajami Y Mortazavi A Khodadadi F Pourfayaz and S

Mohajerzadeh ldquoHighly selective sensor to CH4in presence of

CO and ethanol using LaCoO3perovskite filter with PtSnO

2rdquo

Sensors and Actuators B Chemical vol 117 no 2 pp 420ndash4252006

[33] A Ryzhikov M Labeau and A Gaskov ldquoAl2O3(M=Pt Ru)

catalytic membranes for selective semiconductor gas sensorsrdquoSensors and Actuators B Chemical vol 109 no 1 pp 91ndash962005

[34] J Hubalek K Malysz J Prasek et al ldquoPt-loaded Al2O3

catalytic filters for screen-printed WO3sensors highly selective

to benzenerdquo Sensors and Actuators B Chemical vol 101 no 3pp 277ndash283 2004

[35] M Frietsch F Zudock J Goschnick and M Bruns ldquoCuOcatalytic membrane as selectivity trimmer for metal oxide gassensorsrdquo Sensors and Actuators B Chemical vol 65 no 1ndash3 pp379ndash381 2000

[36] S Liu X Tan and K Li ldquoInorganic membranesrdquo in Encyclope-dia ofMembrane Science andTechnology EMVHoek andVVTarabara Eds vol 1 pp 610ndash638 JohnWileyamp SonsHobokenNJ USA 2013

[37] C Yacou D Wang J Motuzas X Zhang S Smart and J CD da Costa ldquoThin-film ceramic membranesrdquo in Encyclopediaof Membrane Science and Technology E M V Hoek and V VTarabara Eds vol 1 pp 676ndash711 JohnWiley amp Sons HobokenNJ USA 2013

[38] S Basu A Cano-Odena and I F J Vankelecom ldquoAsymmetricMatrimid[Cu

3(BTC)

2]mixed-matrixmembranes for gas sepa-

rationsrdquo Journal of Membrane Science vol 362 no 1-2 pp 478ndash487 2010

[39] P S Tin T S Chung Y Liu R Wang S L Liu andK P Pramoda ldquoEffects of cross-linking modification on gasseparation performance of Matrimid membranesrdquo Journal ofMembrane Science vol 225 no 1-2 pp 77ndash90 2003

[40] Y Zhang IHMusselman J P Ferraris andK J Balkus Jr ldquoGaspermeability properties ofMatrimidmembranes containing themetal-organic framework Cu-BPY-HFSrdquo Journal of MembraneScience vol 313 no 1-2 pp 170ndash181 2008

[41] R Adams J R Johnson C Zhang et al ldquoMixed-matrix mem-branesrdquo in Encyclopedia of Membrane Science and TechnologyE M V Hoek and V V Tarabara Eds vol 1 pp 398ndash430 JohnWiley amp Sons Hoboken NJ USA 2013

[42] T Melin and R Rautenbach Membranverfahren Grundlagender Modul- und Anlagenauslegung vol 3 Springer BerlinGermany 2007

[43] I Voigt and S Tudyka ldquoKeramische membranen und hohl-fasernrdquo in Membranen Grundlagen Verfahren und industrielleAnwendungen K Ohlrogge and K Ebert Eds chapter 5 pp103ndash146 Wiley Weinheim Germany 2006

[44] K Ohlrogge J Wind and K-V Peinemann ldquoVerfahren zurtrennung von gasen und dampfenrdquo inMembranen GrundlagenVerfahren und industrielle Anwendungen K Ohlrogge andK Ebert Eds chapter 12 pp 375ndash428 Wiley WeinheimGermany 2006

[45] X He Q Yu and M-B Hagg ldquoCO2capturerdquo in Encyclopedia

of Membrane Science and Technology E M V Hoek and


V V Tarabara Eds vol 3 pp 1560ndash1588 John Wiley amp SonsHoboken NJ USA 2013

[46] H Lin L S White K lokhandwala and R W Baker ldquoNaturalgas purificationrdquo in Encyclopedia of Membrane Science andTechnology E M V Hoek and V V Tarabara Eds vol 3 pp1644ndash1668 John Wiley amp Sons Hoboken NJ USA 2013

[47] D Rana and T Matsuura ldquoOxygen-nitrogen separationrdquo inEncyclopedia of Membrane Science and Technology E M VHoek and V V Tarabara Eds vol 3 pp 1668ndash1693 JohnWileyamp Sons Hoboken NJ USA 2013

[48] A Brunetti G Barbieri and E Drioli ldquoGas separation applica-tionsrdquo in Encyclopedia of Membrane Science and Technology EM V Hoek V V Tarabara and E Drioli Eds vol 3 pp 1886ndash1915 John Wiley amp Sons Hoboken NJ USA 2013

[49] Y Yampolskii and B FreemanMembrane Gas Separation JohnWiley amp Sons Chichester UK 2010

[50] R W Baker Membrane Technology and Application edited byR W Baker John Wiley amp Sons Chichester UK 3rd edition2012

[51] Y Yampolskii I Pinnau and B Freeman Material Scienceof Membranes for Gas and Vapor Separation edited by YYampolskii I Pinnau and B Freeman John Wiley amp SonsChichester UK 2006

[52] C A Scholes S E Kentish and G W Stevens ldquoThe effectsof minor components on the gas separation performance ofpolymetric membranes for carbon capturerdquo in Membrane GasSeparation Y Yampolskii and B Freeman Eds chapter 11 pp201ndash226 John Wiley amp Sons Chichester UK 2010

[53] H E A Bruschke ldquoPervaporation und dampfpermeationrdquo inMembranen Grundlagen Verfahren und industrielle Anwen-dungen K Ohlrogge and K Ebert Eds chapter 11 pp 335ndash374Wiley Weinheim Germany 2006

[54] A Jonquieres C Arnal-Herault and J Babin ldquoPervaporationrdquoin Encyclopedia of Membrane Science and Technology E M VHoek and V V Tarabara Eds vol 3 pp 1533ndash1560 JohnWileyamp Sons Hoboken NJ USA 2013

[55] A Brunetti P Bernardo E Drioli and G Barbieri ldquoMembraneengineering progress and potentialities in gas separationrdquo inMembrane Gas Separation Y Yampolskii and B Freeman Edschapter 14 pp 281ndash312 John Wiley amp Sons Chichester UK2010

[56] K Nagai ldquoFundamentals and perspectives for pervoparationrdquoin Comprehensive Membrane Science and Engineering Mem-brane Operations in Molecular Separations E Drioli and LGiorno Eds vol 2 pp 243ndash271 Elsevier Kidlington UK 2010

[57] T Uragami ldquoSelective membranes for purification and separa-tion of organic liquid mixturesrdquo in Comprehensive MembraneScience and Engineering Membrane Operations in MolecularSeparations E Drioli and L Giorno Eds vol 2 pp 273ndash324Elsevier Kidlington UK 2010

[58] DGorri A Urtiaga and I Ortiz ldquoSupported liquidmembranesfor pervaporation processesrdquo in Comprehensive MembraneScience and Engineering Membrane Operations in MolecularSeparations E Drioli and L Giorno Eds vol 2 pp 325ndash349Elsevier Kidlington UK 2010

[59] R W BakerMembrane Technology and Applications edited byR W Baker chapter 8 JohnWiley amp Sons Chichester UK 3rdedition 2012

[60] H Domininghaus P Elsner P Eyerer and T HirthKunststoffeEigenschaften und Anwendungen Edited by P Elsner P Eyererand T Hirth Springer Heidelberg Germany 8th edition 2012

[61] W Kaiser ldquoPolyolefinerdquo in Kunststoffchemie fur Ingenieure Vonder Synthese bis zur Anwendung W Kaiser Ed chapter 4 pp235ndash272 Carl Hanser Munchen Germany 3rd edition 2011

[62] W Hellerich G Harsch and E Baur Werkstoff-Fuhrer Kun-ststoffe Eigenschaften Prufungen Kennwerte edited by WHellerich G Harsch and E Baur Carl Hanser MunchenGermany 10th edition 2010

[63] W Kaiser Kunststoffchemie fur Ingenieure Von der Synthesebis zur Anwendung vol 3 of edited by W Kaiser Carl HanserMunchen Germany 2011

[64] H Domininghaus P Elsner P Eyerer and T HirthKunststoffeEigenschaften und Anwendungen edited by P Elsner P EyererT Hirth Springer Heidelberg Germany 8th edition 2012

[65] E Baur S Brinkmann T A Osswald N Rudolph and ESchmachtenberg Saechtling Kunststoff Taschenbuch Edited byH Saechtling Carl Hanser Munchen Germany 31st edition2013

[66] W Hellerich G Harsch and E Baur Werkstoff-Fuhrer Kun-ststoffe Eigenschaften Prufungen Kennwerte Edited by WHellerich G Harsch and E Baur Carl Hanser MunchenGermany 10th edition 2010

[67] W Keim Kunststoffe Synthese Herstellungsverfahren Appara-turen Edited by W Keim Wiley Weinheim Germany 2006

[68] J C Canadas J A Diego J Sellares et al ldquoComparativestudy of amorphous and partially crystalline poly(ethylene-26-naphthalene dicarboxylate) by TSDC DEA DMA and DSCrdquoPolymer vol 41 no 8 pp 2899ndash2905 2000

[69] Goodfellow GmbH 2013 httpwwwgoodfellowcom[70] Reichelt ChemietechnikGmbHampCoThomaplast II Halbzeuge

Reichelt Chemietechnik GmbH amp Co 2012 httpwwwrct-onlinede

[71] P Meares ldquoThe diffusion of gases through polyvinyl acetaterdquoJournal of the American Chemical Society vol 76 no 13 pp3415ndash3422 1954

[72] R Bernstein Y Kaufman andV Freger ldquoMembrane characteri-zationrdquo in Encyclopedia ofMembrane Science and Technology EM V Hoek and V V Tarabara Eds vol 2 pp 1021ndash1062 JohnWiley amp Sons Hoboken NJ USA 2013

[73] Y M Volfkovich A N Filippov and V S Bagotsky StructuralProperties of Porous Materials and Powders Used in DifferentFields of Science and Technology Edited by Y M Volfkovich AN Filippov and VS Bagotsky Springer London UK 2014

[74] S Matteucci Y Yampolskii B D Fremann and I PinnauldquoTransport of gases and vapors in glassy and rubbery polymersrdquoinMaterials Science ofMembranes for Gas andVapor SeparationY Yampolskii I Pinnau and B D Fremann Eds pp 1ndash47 JohnWiley amp Sons Chichester UK 2006

[75] H Strathmann Introduction to Membrane Science and Technol-ogy edited byH StrathmannWileyWeinheim Germany 2011

[76] T Melin and R Rautenbach Membranverfahren Grundlagender Modul- und Anlagenauslegung edited by T Melin RRautenbach Springer Berlin Germany 3rd edition edition2007

[77] J Kappler Characterisation of high-performance SnO2gas sen-

sors for CO detection by in situ techniques [PhD dissertation]Fakultat fur Chemie und Pharmazie Universitat TubingenTubingen Germany 2001

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



the chemical potential In the separation of small moleculeswith diameters of less than 1 nm the reverse osmosis (RO)the diffusion dialysis (DD) or electrodialysis (ED) is usedas the membrane process for the physical state liquidliquidThe separation mechanism is based on a sorption + diffusionin the RO and DD In the ED the mechanism is based onelectrophoretic mobility The driving force is the differenceof the chemical potential (in RO) a concentration difference(in DD) or a difference in electrical potential (in ED) Ifthe physical state is liquidgas the method of choice ispervaporation (PV) The material separation proceeds via asorption + diffusionmechanismThe driving force is a partialpressure difference For separation of gaseous components(gasgas) vapor permeation (VP) and gas permeation (GP)are used The driving force here is a partial pressure just asin pervaporation The mechanism is based on sorption +diffusion In the VP the gases are under standard conditions(21∘C 1 bar) in liquid form and in gaseous form at the GP Forthemembranemethod of VP andGP a variety of commercialand in-process membranes is available Interesting for useas a selective filter in the gas sensors are synthetic solidmembrane materials These comprise organic inorganicor heterogeneous membranes Heterogeneous membranesconsist of a combination of organic and inorganic materials

The organic polymer membranes are in a rubbery-elastichard-elastic or glassy state depending on the glass transi-tion temperature The degree of crystallinity is amorphoussemicrystalline or ideal crystalline For the separation ofgases only dense polymer membranes or polymers havingintrinsic microporosity (PIM) can be used [7] In denseglassy polymer membranes the influence of diffusion is highcompared to the sorption For this reason preferably smallmolecules are transported independently of the polymerThepermeability decreases in the order C

3H8lt CH

4lt N2lt

CO lt O2lt CO

2lt He lt H

2lt H2O In rubbery polymers

the solubility determines the permeability [8] The perme-ability is significantly higher and preferably large moleculesare transported In elastomeric polymers the permeabilitydecreases usually in the order N

2lt He lt O

2lt H2

lt

CH4lt CO

2lt C3H8lt H2O [9] This results in an inverse

correlation Highly permeable elastomeric symmetric poly-mers are usually not very selective while glassy symmetricpolymers have a high selectivity and at the same time a lowpermeability When modified polymers can be adapted tospecific applications Thus a polymer can be functionalizedor its polarity that is hydrophobicityhydrophilicity can bealtered by a chemical modification In addition to a modifi-cation of the membrane material by integration of additivesto establish block- or comb-copolymers surface-controlledchemical modifications may be done One example is fixed-side carrier membranes where suitable carriers are bound ina polymer matrix By fixing of gas molecules a facilitatedselective mass transport through the membrane is achievedby hoppingmechanisms [10] Surface chemical modificationscan be achieved by adsorption without interfering with thestructure (ldquoself-assemblyrdquo coatings) by chemically modi-fying the base material or by using the base material forfurther functionalization The morphology of the polymer isnot or only minimally changed by derivatization grafting

or targeted degradation during chemical modification Thephysical activation is preferably done by UV radiation orplasma treatment During functionalization macromolecularfunctional units are introduced via grafting reactions This iseither a directed coupling by chemical reaction with reactivegroups on the surface (covalent ldquografting-tordquo) or a hetero-geneous radical graft copolymerization with the aid of fixedinitiator groups (ldquografting fromrdquo) Using these functionalgroups the surface properties can be optimized [11ndash14] withregard to polarity hydrophilicityhydrophobicity and theresistance to fouling

Using asymmetric polymers the permeability can beincreased by a factor of at least fifty up to one hundredwhile maintaining a constant selectivity Asymmetric poly-mers consist of a dense barrier layer having a thickness of005ndash05 120583m The separation layer is stabilized by a poroussupporting layer (30ndash200120583m) The pore size increases withdistance from the separating layer They involve integral-asymmetric membranes consisting of a polymer or com-posite materials in which the active layer and the supportlayer aremanufactured fromdifferentmaterials In compositematerials the properties of the individual layers can beoptimally adapted to a separation problem Since it is difficultto apply a thin release layer on a porous structure a smoothhighly permeable intermediate layer is often applied Verythin separation layers are prone to build up pinholes whichmay result in Knudsen diffusion or an unselective viscous gasflow Such pinholes can be sealed with a silicone coatingTheseparation factor is only minimally affected by such a coverlayer An overview of gas-selective polymer membranes isgiven in [9 15 16] in combination with gas sensors in [17 18]

On the other hand inorganic membranes for specialapplications of microfiltration (MF) and ultrafiltration (UF)are now established Among these are silica-based mem-branes of high importance [19ndash23] but also zeolites [24ndash30]Other materials involve perovskites [31 32] Al

2O3[19 33

34] or copper oxide [35] Compared to polymers inorganicmembranes have the following advantages the cut-off andseparation sharpness can be better controlled The mem-branes are characterized by a higher temperature resistancea lower aging and better chemical resistance (no membraneswelling) Among symmetric porous inorganic membranesfor gas separation the carbon membrane is important How-ever inorganic membranes have the following disadvantageslimiting their application as GP membranes the materialsare mostly brittle and require a multilayered structure whichalso involves several steps The production is therefore moreexpensive than for comparable polymer membranes There-fore themembranes are simply too expensive for applicationsin gas sensor technologyTherefore inorganicmembranes arenot described here in detail instead we refer to overviews ofgas-selective inorganic membranes given in [36 37]

Another class the so-called mixed matrix membranes(MMM) consists of a combination of inorganic and organicmaterials [38ndash40] The selectivity and the permeability ofthe membrane can be calculated in advance from the dataof the homogeneous materials The company Creavis pro-vides flexible ceramic flat membranes under the trade nameCreafilterThismembrane consists of a supportmade ofmetal




2N2 N2CH4 SO2CH4

H2N2 HeN

2 CO

2N2 CO

2CH4 H2CO2 SO2CO2

H2CO and H





2and CH

4from Matrimid and


2OCH




2CO) (H

2CH4) (O

2N2) (CO

2N2)

(CO2CH4) (H2OCH

4) (H2OLuft) PS (H

2N2) (O2N2)

(H2CO) (H

2CH4) PA (H

2OCH

4) (CO

2CH4) PC

(O2N2) CA (O

2N2) (H2OCH

4) (CO

2CH4) (H2CH4)

(H2CO) (H

2N2) PPO (O

2N2) (CO

2CH4) fluoropoly-


2CO) (H

2CH4)




2 CO CO









CC

H H

HHn

lowast lowast

(a)

CH

n

lowast lowastCH2

CH3

(b)

CHn

lowast lowastCH2

CH3

CH3

(c)

n

lowast

lowastCH3

CH3

O

O

O

(d)

n

lowast lowast

O O

OO

(e)

nlowast

lowast

O

O

OO

(f)

n

lowast lowastO O C

O

(g)

H

n

lowastlowast

O

N

(h)

nlowast

lowast

O

O

O

O

O

N

N

(i)

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

(j)

n

lowast lowastS

O

O

O

(k)
























(GF)


(GF)



(RCT)


(GF)





13(GF)



122 267 155 04 136 12(GF)




12(GF)


minus8 2855 230 80ndash100 27 113 15

(GF)













119894) pressure (119901

119894)




Gas A



Permeate

Vmf

(a)

Feed

Membrane

PermeateΔz

pf

120583fgi

Xfi

pfi

Cfmi

Cpmi

Xpi

ppi

pp

120583pgi

Ji

120583pi minus 120583

fi

(b)






119894minus 120583119891




119869119894= minus119862119898

119894sdot 119887119898

119894sdot

119889120583119898

119894

119889119911

(2)




Einstein equation

119863119898

119894= 119877 sdot 119879 sdot 119887

119898

119894 (3)


119869119894= minus119862119898

119894sdot

119863119898

119894

119877 sdot 119879

sdot

119889120583119898

119894

119889119911

= minus119871119894sdot

119889120583119898

119894

119889119911

(4)

Here 119869119894is the flux 119871



119889120583119894

119889119911

=

1

119889119911

sdot (119881119894119889119901 + 119877119879119889 ln 119886

119894) (5)


119894

can be derived

119869119894= minus119871119894

1

119889119911

(119877119879119889 ln 119886119898119894+ 119881119894119889119901) (6)



119869119894= minus119871119894119877119879

119889 ln 119886119898119894

119889119911

=

119871119894119877119879

119886119898

119894

sdot

119889119886119898

119894

119889119911

(7)


119869119894= minus119871119894

119877119879

119886119898

119894

sdot

119886119898119901

119894minus 119886119898119891

119894

Δ119911

(8)



119886119898119891

119894=

119886119892119891

119894sdot 119901119891

1199010

119894

119886119898119901

119894=

119886119892119901

119894sdot 119901119901

1199010

119894

(9)




expression

119869119894= minus119871119894

119877119879

119886119898

119894sdot1199010

119894

sdot

119886119892119901

119894sdot 119901119901minus 119886119892119891

119894sdot 119901119891

Δ119911

(10)




coefficient (119863119898119894) is

119862119898

119894=

120588119898

119894

119872119894

sdot

120593119894sdot 119901119894

120574119894sdot 1199010

119894

=

120588119898

119894

119872119894

sdot 119883119898

119894 119871119894=

119863119898

119894sdot 119862119898

119894

119877119879

(11)


119894= 120593119865


119869119894= minus119863119898

119894sdot

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

= minus119863119898

119894sdot 119896119894sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

(12)


119894the fugacity






119894)

119875119894= 119863119894sdot 119896119894 (13)




119863119894= 1198630exp (119864119863

119877119879

) (14)


0a preexpo-



119864119863= 025 sdot 119873

0sdot 120587 sdot 119889


119864coh119881119898

(15)






1198630=

120582 sdot 120592th2

(16)



2 H2 and CO

2) The FFV



119863119894= 119860119894exp(

119861119894

FFV)mit FFV =

119881119898minus 119881119894119900

119881119898

=

119881119898minus 13 sdot 119881

119882

119881119898

(17)

119860119894and 119861






119882 The FFV is


119863119894= 119860lowast

119894exp(

minus119861lowast

119894

1 minus 119886

)mit 119886 = 13 sdot119881119882

119875119871119871

sdot

120576 minus 1

120576 + 2

(18)

Here 119860lowast119894and 119861

lowast


119882the specific




119894


119896119894=

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

=

119862119898

119894

119901119894

(19)



119894the



119896119894= 1198960exp(minus

Δ119867119878

119877119879

)mit Δ119867119878= Δ119867

119898+ Δ119867119888

Δ119866119898= Δ119867

119898minus 119879Δ119878

119898

(20)










Δ119867119898= 119867119891119897+ 119867Pol minus 2 sdot 119867

119891119897-Pol (21)

Here 119867119891119897



Δ119867119898= 119881 sdot (120575

119891119897minus 120575Pol)

2

sdot 120601119891119897sdot 120601Pol mit 120575

= (

119864coh119881

)

12

(22)


119898lt 119879Δ119878



119891119897asymp 120575Pol




as

119877119894= (1 minus

119862119901

119894

119862119891

119894

) (23)


119898



119862119898

119894= 119896119894sdot 119901119894= 119870119867

119894sdot 119901119894 (24)








119862119894= 119862119867

119894+ 119862119871

119894= 119870119867

119894sdot 119901119894+

1198621198711015840

119894119887119901119894

1 + 119887119901119894

(25)



119870119867



1015840

119894the


119878119875

119895119896=

119875119895

119875119896

= 119878119863

119895119896sdot 119878119896

119895119896 (26)

The selectivity 119878119901119895119896


120572119895119896

=

119883119901

119895

119883119891

119895

119883119891

119896

119883119901

119896

=

119883119901

119895sdot (1 minus 119883

119891

119895)

119883119891

119895sdot (1 minus 119883

119901

119895)

(27)


120572119895119896

= 119878119895119896

((119883119901

119895sdot 119901119901) 119901119891minus 119883119891

119895)

((119883119901

119896sdot 119901119901) 119901119891minus 119883119891

119896)

119883119891

119896

119883119891

119895

(28)


lim119901119901119901119891rarr0

120572119895119896

= 119878119895119896 (29)










119904is slightly












4 ethanol








(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)



119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)




1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)


1199091015840

















(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












2N2 N2CH4 SO2CH4

H2N2 HeN

2 CO

2N2 CO

2CH4 H2CO2 SO2CO2

H2CO and H





2and CH

4from Matrimid and


2OCH




2CO) (H

2CH4) (O

2N2) (CO

2N2)

(CO2CH4) (H2OCH

4) (H2OLuft) PS (H

2N2) (O2N2)

(H2CO) (H

2CH4) PA (H

2OCH

4) (CO

2CH4) PC

(O2N2) CA (O

2N2) (H2OCH

4) (CO

2CH4) (H2CH4)

(H2CO) (H

2N2) PPO (O

2N2) (CO

2CH4) fluoropoly-


2CO) (H

2CH4)




2 CO CO









CC

H H

HHn

lowast lowast

(a)

CH

n

lowast lowastCH2

CH3

(b)

CHn

lowast lowastCH2

CH3

CH3

(c)

n

lowast

lowastCH3

CH3

O

O

O

(d)

n

lowast lowast

O O

OO

(e)

nlowast

lowast

O

O

OO

(f)

n

lowast lowastO O C

O

(g)

H

n

lowastlowast

O

N

(h)

nlowast

lowast

O

O

O

O

O

N

N

(i)

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

(j)

n

lowast lowastS

O

O

O

(k)
























(GF)


(GF)



(RCT)


(GF)





13(GF)



122 267 155 04 136 12(GF)




12(GF)


minus8 2855 230 80ndash100 27 113 15

(GF)













119894) pressure (119901

119894)




Gas A



Permeate

Vmf

(a)

Feed

Membrane

PermeateΔz

pf

120583fgi

Xfi

pfi

Cfmi

Cpmi

Xpi

ppi

pp

120583pgi

Ji

120583pi minus 120583

fi

(b)






119894minus 120583119891




119869119894= minus119862119898

119894sdot 119887119898

119894sdot

119889120583119898

119894

119889119911

(2)




Einstein equation

119863119898

119894= 119877 sdot 119879 sdot 119887

119898

119894 (3)


119869119894= minus119862119898

119894sdot

119863119898

119894

119877 sdot 119879

sdot

119889120583119898

119894

119889119911

= minus119871119894sdot

119889120583119898

119894

119889119911

(4)

Here 119869119894is the flux 119871



119889120583119894

119889119911

=

1

119889119911

sdot (119881119894119889119901 + 119877119879119889 ln 119886

119894) (5)


119894

can be derived

119869119894= minus119871119894

1

119889119911

(119877119879119889 ln 119886119898119894+ 119881119894119889119901) (6)



119869119894= minus119871119894119877119879

119889 ln 119886119898119894

119889119911

=

119871119894119877119879

119886119898

119894

sdot

119889119886119898

119894

119889119911

(7)


119869119894= minus119871119894

119877119879

119886119898

119894

sdot

119886119898119901

119894minus 119886119898119891

119894

Δ119911

(8)



119886119898119891

119894=

119886119892119891

119894sdot 119901119891

1199010

119894

119886119898119901

119894=

119886119892119901

119894sdot 119901119901

1199010

119894

(9)




expression

119869119894= minus119871119894

119877119879

119886119898

119894sdot1199010

119894

sdot

119886119892119901

119894sdot 119901119901minus 119886119892119891

119894sdot 119901119891

Δ119911

(10)




coefficient (119863119898119894) is

119862119898

119894=

120588119898

119894

119872119894

sdot

120593119894sdot 119901119894

120574119894sdot 1199010

119894

=

120588119898

119894

119872119894

sdot 119883119898

119894 119871119894=

119863119898

119894sdot 119862119898

119894

119877119879

(11)


119894= 120593119865


119869119894= minus119863119898

119894sdot

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

= minus119863119898

119894sdot 119896119894sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

(12)


119894the fugacity






119894)

119875119894= 119863119894sdot 119896119894 (13)




119863119894= 1198630exp (119864119863

119877119879

) (14)


0a preexpo-



119864119863= 025 sdot 119873

0sdot 120587 sdot 119889


119864coh119881119898

(15)






1198630=

120582 sdot 120592th2

(16)



2 H2 and CO

2) The FFV



119863119894= 119860119894exp(

119861119894

FFV)mit FFV =

119881119898minus 119881119894119900

119881119898

=

119881119898minus 13 sdot 119881

119882

119881119898

(17)

119860119894and 119861






119882 The FFV is


119863119894= 119860lowast

119894exp(

minus119861lowast

119894

1 minus 119886

)mit 119886 = 13 sdot119881119882

119875119871119871

sdot

120576 minus 1

120576 + 2

(18)

Here 119860lowast119894and 119861

lowast


119882the specific




119894


119896119894=

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

=

119862119898

119894

119901119894

(19)



119894the



119896119894= 1198960exp(minus

Δ119867119878

119877119879

)mit Δ119867119878= Δ119867

119898+ Δ119867119888

Δ119866119898= Δ119867

119898minus 119879Δ119878

119898

(20)










Δ119867119898= 119867119891119897+ 119867Pol minus 2 sdot 119867

119891119897-Pol (21)

Here 119867119891119897



Δ119867119898= 119881 sdot (120575

119891119897minus 120575Pol)

2

sdot 120601119891119897sdot 120601Pol mit 120575

= (

119864coh119881

)

12

(22)


119898lt 119879Δ119878



119891119897asymp 120575Pol




as

119877119894= (1 minus

119862119901

119894

119862119891

119894

) (23)


119898



119862119898

119894= 119896119894sdot 119901119894= 119870119867

119894sdot 119901119894 (24)








119862119894= 119862119867

119894+ 119862119871

119894= 119870119867

119894sdot 119901119894+

1198621198711015840

119894119887119901119894

1 + 119887119901119894

(25)



119870119867



1015840

119894the


119878119875

119895119896=

119875119895

119875119896

= 119878119863

119895119896sdot 119878119896

119895119896 (26)

The selectivity 119878119901119895119896


120572119895119896

=

119883119901

119895

119883119891

119895

119883119891

119896

119883119901

119896

=

119883119901

119895sdot (1 minus 119883

119891

119895)

119883119891

119895sdot (1 minus 119883

119901

119895)

(27)


120572119895119896

= 119878119895119896

((119883119901

119895sdot 119901119901) 119901119891minus 119883119891

119895)

((119883119901

119896sdot 119901119901) 119901119891minus 119883119891

119896)

119883119891

119896

119883119891

119895

(28)


lim119901119901119901119891rarr0

120572119895119896

= 119878119895119896 (29)










119904is slightly












4 ethanol








(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)



119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)




1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)


1199091015840

















(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










CC

H H

HHn

lowast lowast

(a)

CH

n

lowast lowastCH2

CH3

(b)

CHn

lowast lowastCH2

CH3

CH3

(c)

n

lowast

lowastCH3

CH3

O

O

O

(d)

n

lowast lowast

O O

OO

(e)

nlowast

lowast

O

O

OO

(f)

n

lowast lowastO O C

O

(g)

H

n

lowastlowast

O

N

(h)

nlowast

lowast

O

O

O

O

O

N

N

(i)

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

(j)

n

lowast lowastS

O

O

O

(k)
























(GF)


(GF)



(RCT)


(GF)





13(GF)



122 267 155 04 136 12(GF)




12(GF)


minus8 2855 230 80ndash100 27 113 15

(GF)













119894) pressure (119901

119894)




Gas A



Permeate

Vmf

(a)

Feed

Membrane

PermeateΔz

pf

120583fgi

Xfi

pfi

Cfmi

Cpmi

Xpi

ppi

pp

120583pgi

Ji

120583pi minus 120583

fi

(b)






119894minus 120583119891




119869119894= minus119862119898

119894sdot 119887119898

119894sdot

119889120583119898

119894

119889119911

(2)




Einstein equation

119863119898

119894= 119877 sdot 119879 sdot 119887

119898

119894 (3)


119869119894= minus119862119898

119894sdot

119863119898

119894

119877 sdot 119879

sdot

119889120583119898

119894

119889119911

= minus119871119894sdot

119889120583119898

119894

119889119911

(4)

Here 119869119894is the flux 119871



119889120583119894

119889119911

=

1

119889119911

sdot (119881119894119889119901 + 119877119879119889 ln 119886

119894) (5)


119894

can be derived

119869119894= minus119871119894

1

119889119911

(119877119879119889 ln 119886119898119894+ 119881119894119889119901) (6)



119869119894= minus119871119894119877119879

119889 ln 119886119898119894

119889119911

=

119871119894119877119879

119886119898

119894

sdot

119889119886119898

119894

119889119911

(7)


119869119894= minus119871119894

119877119879

119886119898

119894

sdot

119886119898119901

119894minus 119886119898119891

119894

Δ119911

(8)



119886119898119891

119894=

119886119892119891

119894sdot 119901119891

1199010

119894

119886119898119901

119894=

119886119892119901

119894sdot 119901119901

1199010

119894

(9)




expression

119869119894= minus119871119894

119877119879

119886119898

119894sdot1199010

119894

sdot

119886119892119901

119894sdot 119901119901minus 119886119892119891

119894sdot 119901119891

Δ119911

(10)




coefficient (119863119898119894) is

119862119898

119894=

120588119898

119894

119872119894

sdot

120593119894sdot 119901119894

120574119894sdot 1199010

119894

=

120588119898

119894

119872119894

sdot 119883119898

119894 119871119894=

119863119898

119894sdot 119862119898

119894

119877119879

(11)


119894= 120593119865


119869119894= minus119863119898

119894sdot

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

= minus119863119898

119894sdot 119896119894sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

(12)


119894the fugacity






119894)

119875119894= 119863119894sdot 119896119894 (13)




119863119894= 1198630exp (119864119863

119877119879

) (14)


0a preexpo-



119864119863= 025 sdot 119873

0sdot 120587 sdot 119889


119864coh119881119898

(15)






1198630=

120582 sdot 120592th2

(16)



2 H2 and CO

2) The FFV



119863119894= 119860119894exp(

119861119894

FFV)mit FFV =

119881119898minus 119881119894119900

119881119898

=

119881119898minus 13 sdot 119881

119882

119881119898

(17)

119860119894and 119861






119882 The FFV is


119863119894= 119860lowast

119894exp(

minus119861lowast

119894

1 minus 119886

)mit 119886 = 13 sdot119881119882

119875119871119871

sdot

120576 minus 1

120576 + 2

(18)

Here 119860lowast119894and 119861

lowast


119882the specific




119894


119896119894=

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

=

119862119898

119894

119901119894

(19)



119894the



119896119894= 1198960exp(minus

Δ119867119878

119877119879

)mit Δ119867119878= Δ119867

119898+ Δ119867119888

Δ119866119898= Δ119867

119898minus 119879Δ119878

119898

(20)










Δ119867119898= 119867119891119897+ 119867Pol minus 2 sdot 119867

119891119897-Pol (21)

Here 119867119891119897



Δ119867119898= 119881 sdot (120575

119891119897minus 120575Pol)

2

sdot 120601119891119897sdot 120601Pol mit 120575

= (

119864coh119881

)

12

(22)


119898lt 119879Δ119878



119891119897asymp 120575Pol




as

119877119894= (1 minus

119862119901

119894

119862119891

119894

) (23)


119898



119862119898

119894= 119896119894sdot 119901119894= 119870119867

119894sdot 119901119894 (24)








119862119894= 119862119867

119894+ 119862119871

119894= 119870119867

119894sdot 119901119894+

1198621198711015840

119894119887119901119894

1 + 119887119901119894

(25)



119870119867



1015840

119894the


119878119875

119895119896=

119875119895

119875119896

= 119878119863

119895119896sdot 119878119896

119895119896 (26)

The selectivity 119878119901119895119896


120572119895119896

=

119883119901

119895

119883119891

119895

119883119891

119896

119883119901

119896

=

119883119901

119895sdot (1 minus 119883

119891

119895)

119883119891

119895sdot (1 minus 119883

119901

119895)

(27)


120572119895119896

= 119878119895119896

((119883119901

119895sdot 119901119901) 119901119891minus 119883119891

119895)

((119883119901

119896sdot 119901119901) 119901119891minus 119883119891

119896)

119883119891

119896

119883119891

119895

(28)


lim119901119901119901119891rarr0

120572119895119896

= 119878119895119896 (29)










119904is slightly












4 ethanol








(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)



119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)




1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)


1199091015840

















(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation


























(GF)


(GF)



(RCT)


(GF)





13(GF)



122 267 155 04 136 12(GF)




12(GF)


minus8 2855 230 80ndash100 27 113 15

(GF)













119894) pressure (119901

119894)




Gas A



Permeate

Vmf

(a)

Feed

Membrane

PermeateΔz

pf

120583fgi

Xfi

pfi

Cfmi

Cpmi

Xpi

ppi

pp

120583pgi

Ji

120583pi minus 120583

fi

(b)






119894minus 120583119891




119869119894= minus119862119898

119894sdot 119887119898

119894sdot

119889120583119898

119894

119889119911

(2)




Einstein equation

119863119898

119894= 119877 sdot 119879 sdot 119887

119898

119894 (3)


119869119894= minus119862119898

119894sdot

119863119898

119894

119877 sdot 119879

sdot

119889120583119898

119894

119889119911

= minus119871119894sdot

119889120583119898

119894

119889119911

(4)

Here 119869119894is the flux 119871



119889120583119894

119889119911

=

1

119889119911

sdot (119881119894119889119901 + 119877119879119889 ln 119886

119894) (5)


119894

can be derived

119869119894= minus119871119894

1

119889119911

(119877119879119889 ln 119886119898119894+ 119881119894119889119901) (6)



119869119894= minus119871119894119877119879

119889 ln 119886119898119894

119889119911

=

119871119894119877119879

119886119898

119894

sdot

119889119886119898

119894

119889119911

(7)


119869119894= minus119871119894

119877119879

119886119898

119894

sdot

119886119898119901

119894minus 119886119898119891

119894

Δ119911

(8)



119886119898119891

119894=

119886119892119891

119894sdot 119901119891

1199010

119894

119886119898119901

119894=

119886119892119901

119894sdot 119901119901

1199010

119894

(9)




expression

119869119894= minus119871119894

119877119879

119886119898

119894sdot1199010

119894

sdot

119886119892119901

119894sdot 119901119901minus 119886119892119891

119894sdot 119901119891

Δ119911

(10)




coefficient (119863119898119894) is

119862119898

119894=

120588119898

119894

119872119894

sdot

120593119894sdot 119901119894

120574119894sdot 1199010

119894

=

120588119898

119894

119872119894

sdot 119883119898

119894 119871119894=

119863119898

119894sdot 119862119898

119894

119877119879

(11)


119894= 120593119865


119869119894= minus119863119898

119894sdot

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

= minus119863119898

119894sdot 119896119894sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

(12)


119894the fugacity






119894)

119875119894= 119863119894sdot 119896119894 (13)




119863119894= 1198630exp (119864119863

119877119879

) (14)


0a preexpo-



119864119863= 025 sdot 119873

0sdot 120587 sdot 119889


119864coh119881119898

(15)






1198630=

120582 sdot 120592th2

(16)



2 H2 and CO

2) The FFV



119863119894= 119860119894exp(

119861119894

FFV)mit FFV =

119881119898minus 119881119894119900

119881119898

=

119881119898minus 13 sdot 119881

119882

119881119898

(17)

119860119894and 119861






119882 The FFV is


119863119894= 119860lowast

119894exp(

minus119861lowast

119894

1 minus 119886

)mit 119886 = 13 sdot119881119882

119875119871119871

sdot

120576 minus 1

120576 + 2

(18)

Here 119860lowast119894and 119861

lowast


119882the specific




119894


119896119894=

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

=

119862119898

119894

119901119894

(19)



119894the



119896119894= 1198960exp(minus

Δ119867119878

119877119879

)mit Δ119867119878= Δ119867

119898+ Δ119867119888

Δ119866119898= Δ119867

119898minus 119879Δ119878

119898

(20)










Δ119867119898= 119867119891119897+ 119867Pol minus 2 sdot 119867

119891119897-Pol (21)

Here 119867119891119897



Δ119867119898= 119881 sdot (120575

119891119897minus 120575Pol)

2

sdot 120601119891119897sdot 120601Pol mit 120575

= (

119864coh119881

)

12

(22)


119898lt 119879Δ119878



119891119897asymp 120575Pol




as

119877119894= (1 minus

119862119901

119894

119862119891

119894

) (23)


119898



119862119898

119894= 119896119894sdot 119901119894= 119870119867

119894sdot 119901119894 (24)








119862119894= 119862119867

119894+ 119862119871

119894= 119870119867

119894sdot 119901119894+

1198621198711015840

119894119887119901119894

1 + 119887119901119894

(25)



119870119867



1015840

119894the


119878119875

119895119896=

119875119895

119875119896

= 119878119863

119895119896sdot 119878119896

119895119896 (26)

The selectivity 119878119901119895119896


120572119895119896

=

119883119901

119895

119883119891

119895

119883119891

119896

119883119901

119896

=

119883119901

119895sdot (1 minus 119883

119891

119895)

119883119891

119895sdot (1 minus 119883

119901

119895)

(27)


120572119895119896

= 119878119895119896

((119883119901

119895sdot 119901119901) 119901119891minus 119883119891

119895)

((119883119901

119896sdot 119901119901) 119901119891minus 119883119891

119896)

119883119891

119896

119883119891

119895

(28)


lim119901119901119901119891rarr0

120572119895119896

= 119878119895119896 (29)










119904is slightly












4 ethanol








(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)



119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)




1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)


1199091015840

















(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Gas A



Permeate

Vmf

(a)

Feed

Membrane

PermeateΔz

pf

120583fgi

Xfi

pfi

Cfmi

Cpmi

Xpi

ppi

pp

120583pgi

Ji

120583pi minus 120583

fi

(b)






119894minus 120583119891




119869119894= minus119862119898

119894sdot 119887119898

119894sdot

119889120583119898

119894

119889119911

(2)




Einstein equation

119863119898

119894= 119877 sdot 119879 sdot 119887

119898

119894 (3)


119869119894= minus119862119898

119894sdot

119863119898

119894

119877 sdot 119879

sdot

119889120583119898

119894

119889119911

= minus119871119894sdot

119889120583119898

119894

119889119911

(4)

Here 119869119894is the flux 119871



119889120583119894

119889119911

=

1

119889119911

sdot (119881119894119889119901 + 119877119879119889 ln 119886

119894) (5)


119894

can be derived

119869119894= minus119871119894

1

119889119911

(119877119879119889 ln 119886119898119894+ 119881119894119889119901) (6)



119869119894= minus119871119894119877119879

119889 ln 119886119898119894

119889119911

=

119871119894119877119879

119886119898

119894

sdot

119889119886119898

119894

119889119911

(7)


119869119894= minus119871119894

119877119879

119886119898

119894

sdot

119886119898119901

119894minus 119886119898119891

119894

Δ119911

(8)



119886119898119891

119894=

119886119892119891

119894sdot 119901119891

1199010

119894

119886119898119901

119894=

119886119892119901

119894sdot 119901119901

1199010

119894

(9)




expression

119869119894= minus119871119894

119877119879

119886119898

119894sdot1199010

119894

sdot

119886119892119901

119894sdot 119901119901minus 119886119892119891

119894sdot 119901119891

Δ119911

(10)




coefficient (119863119898119894) is

119862119898

119894=

120588119898

119894

119872119894

sdot

120593119894sdot 119901119894

120574119894sdot 1199010

119894

=

120588119898

119894

119872119894

sdot 119883119898

119894 119871119894=

119863119898

119894sdot 119862119898

119894

119877119879

(11)


119894= 120593119865


119869119894= minus119863119898

119894sdot

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

= minus119863119898

119894sdot 119896119894sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

(12)


119894the fugacity






119894)

119875119894= 119863119894sdot 119896119894 (13)




119863119894= 1198630exp (119864119863

119877119879

) (14)


0a preexpo-



119864119863= 025 sdot 119873

0sdot 120587 sdot 119889


119864coh119881119898

(15)






1198630=

120582 sdot 120592th2

(16)



2 H2 and CO

2) The FFV



119863119894= 119860119894exp(

119861119894

FFV)mit FFV =

119881119898minus 119881119894119900

119881119898

=

119881119898minus 13 sdot 119881

119882

119881119898

(17)

119860119894and 119861






119882 The FFV is


119863119894= 119860lowast

119894exp(

minus119861lowast

119894

1 minus 119886

)mit 119886 = 13 sdot119881119882

119875119871119871

sdot

120576 minus 1

120576 + 2

(18)

Here 119860lowast119894and 119861

lowast


119882the specific




119894


119896119894=

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

=

119862119898

119894

119901119894

(19)



119894the



119896119894= 1198960exp(minus

Δ119867119878

119877119879

)mit Δ119867119878= Δ119867

119898+ Δ119867119888

Δ119866119898= Δ119867

119898minus 119879Δ119878

119898

(20)










Δ119867119898= 119867119891119897+ 119867Pol minus 2 sdot 119867

119891119897-Pol (21)

Here 119867119891119897



Δ119867119898= 119881 sdot (120575

119891119897minus 120575Pol)

2

sdot 120601119891119897sdot 120601Pol mit 120575

= (

119864coh119881

)

12

(22)


119898lt 119879Δ119878



119891119897asymp 120575Pol




as

119877119894= (1 minus

119862119901

119894

119862119891

119894

) (23)


119898



119862119898

119894= 119896119894sdot 119901119894= 119870119867

119894sdot 119901119894 (24)








119862119894= 119862119867

119894+ 119862119871

119894= 119870119867

119894sdot 119901119894+

1198621198711015840

119894119887119901119894

1 + 119887119901119894

(25)



119870119867



1015840

119894the


119878119875

119895119896=

119875119895

119875119896

= 119878119863

119895119896sdot 119878119896

119895119896 (26)

The selectivity 119878119901119895119896


120572119895119896

=

119883119901

119895

119883119891

119895

119883119891

119896

119883119901

119896

=

119883119901

119895sdot (1 minus 119883

119891

119895)

119883119891

119895sdot (1 minus 119883

119901

119895)

(27)


120572119895119896

= 119878119895119896

((119883119901

119895sdot 119901119901) 119901119891minus 119883119891

119895)

((119883119901

119896sdot 119901119901) 119901119891minus 119883119891

119896)

119883119891

119896

119883119891

119895

(28)


lim119901119901119901119891rarr0

120572119895119896

= 119878119895119896 (29)










119904is slightly












4 ethanol








(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)



119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)




1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)


1199091015840

















(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











119869119894= minus119871119894119877119879

119889 ln 119886119898119894

119889119911

=

119871119894119877119879

119886119898

119894

sdot

119889119886119898

119894

119889119911

(7)


119869119894= minus119871119894

119877119879

119886119898

119894

sdot

119886119898119901

119894minus 119886119898119891

119894

Δ119911

(8)



119886119898119891

119894=

119886119892119891

119894sdot 119901119891

1199010

119894

119886119898119901

119894=

119886119892119901

119894sdot 119901119901

1199010

119894

(9)




expression

119869119894= minus119871119894

119877119879

119886119898

119894sdot1199010

119894

sdot

119886119892119901

119894sdot 119901119901minus 119886119892119891

119894sdot 119901119891

Δ119911

(10)




coefficient (119863119898119894) is

119862119898

119894=

120588119898

119894

119872119894

sdot

120593119894sdot 119901119894

120574119894sdot 1199010

119894

=

120588119898

119894

119872119894

sdot 119883119898

119894 119871119894=

119863119898

119894sdot 119862119898

119894

119877119879

(11)


119894= 120593119865


119869119894= minus119863119898

119894sdot

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

= minus119863119898

119894sdot 119896119894sdot (

119901119901

119894minus 119901119891

119894

Δ119911

)

(12)


119894the fugacity






119894)

119875119894= 119863119894sdot 119896119894 (13)




119863119894= 1198630exp (119864119863

119877119879

) (14)


0a preexpo-



119864119863= 025 sdot 119873

0sdot 120587 sdot 119889


119864coh119881119898

(15)






1198630=

120582 sdot 120592th2

(16)



2 H2 and CO

2) The FFV



119863119894= 119860119894exp(

119861119894

FFV)mit FFV =

119881119898minus 119881119894119900

119881119898

=

119881119898minus 13 sdot 119881

119882

119881119898

(17)

119860119894and 119861






119882 The FFV is


119863119894= 119860lowast

119894exp(

minus119861lowast

119894

1 minus 119886

)mit 119886 = 13 sdot119881119882

119875119871119871

sdot

120576 minus 1

120576 + 2

(18)

Here 119860lowast119894and 119861

lowast


119882the specific




119894


119896119894=

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

=

119862119898

119894

119901119894

(19)



119894the



119896119894= 1198960exp(minus

Δ119867119878

119877119879

)mit Δ119867119878= Δ119867

119898+ Δ119867119888

Δ119866119898= Δ119867

119898minus 119879Δ119878

119898

(20)










Δ119867119898= 119867119891119897+ 119867Pol minus 2 sdot 119867

119891119897-Pol (21)

Here 119867119891119897



Δ119867119898= 119881 sdot (120575

119891119897minus 120575Pol)

2

sdot 120601119891119897sdot 120601Pol mit 120575

= (

119864coh119881

)

12

(22)


119898lt 119879Δ119878



119891119897asymp 120575Pol




as

119877119894= (1 minus

119862119901

119894

119862119891

119894

) (23)


119898



119862119898

119894= 119896119894sdot 119901119894= 119870119867

119894sdot 119901119894 (24)








119862119894= 119862119867

119894+ 119862119871

119894= 119870119867

119894sdot 119901119894+

1198621198711015840

119894119887119901119894

1 + 119887119901119894

(25)



119870119867



1015840

119894the


119878119875

119895119896=

119875119895

119875119896

= 119878119863

119895119896sdot 119878119896

119895119896 (26)

The selectivity 119878119901119895119896


120572119895119896

=

119883119901

119895

119883119891

119895

119883119891

119896

119883119901

119896

=

119883119901

119895sdot (1 minus 119883

119891

119895)

119883119891

119895sdot (1 minus 119883

119901

119895)

(27)


120572119895119896

= 119878119895119896

((119883119901

119895sdot 119901119901) 119901119891minus 119883119891

119895)

((119883119901

119896sdot 119901119901) 119901119891minus 119883119891

119896)

119883119891

119896

119883119891

119895

(28)


lim119901119901119901119891rarr0

120572119895119896

= 119878119895119896 (29)










119904is slightly












4 ethanol








(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)



119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)




1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)


1199091015840

















(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











119863119894= 119860119894exp(

119861119894

FFV)mit FFV =

119881119898minus 119881119894119900

119881119898

=

119881119898minus 13 sdot 119881

119882

119881119898

(17)

119860119894and 119861






119882 The FFV is


119863119894= 119860lowast

119894exp(

minus119861lowast

119894

1 minus 119886

)mit 119886 = 13 sdot119881119882

119875119871119871

sdot

120576 minus 1

120576 + 2

(18)

Here 119860lowast119894and 119861

lowast


119882the specific




119894


119896119894=

120593119894sdot 120588119898

119894

120574119894sdot 1199010

119894sdot 119872119894

=

119862119898

119894

119901119894

(19)



119894the



119896119894= 1198960exp(minus

Δ119867119878

119877119879

)mit Δ119867119878= Δ119867

119898+ Δ119867119888

Δ119866119898= Δ119867

119898minus 119879Δ119878

119898

(20)










Δ119867119898= 119867119891119897+ 119867Pol minus 2 sdot 119867

119891119897-Pol (21)

Here 119867119891119897



Δ119867119898= 119881 sdot (120575

119891119897minus 120575Pol)

2

sdot 120601119891119897sdot 120601Pol mit 120575

= (

119864coh119881

)

12

(22)


119898lt 119879Δ119878



119891119897asymp 120575Pol




as

119877119894= (1 minus

119862119901

119894

119862119891

119894

) (23)


119898



119862119898

119894= 119896119894sdot 119901119894= 119870119867

119894sdot 119901119894 (24)








119862119894= 119862119867

119894+ 119862119871

119894= 119870119867

119894sdot 119901119894+

1198621198711015840

119894119887119901119894

1 + 119887119901119894

(25)



119870119867



1015840

119894the


119878119875

119895119896=

119875119895

119875119896

= 119878119863

119895119896sdot 119878119896

119895119896 (26)

The selectivity 119878119901119895119896


120572119895119896

=

119883119901

119895

119883119891

119895

119883119891

119896

119883119901

119896

=

119883119901

119895sdot (1 minus 119883

119891

119895)

119883119891

119895sdot (1 minus 119883

119901

119895)

(27)


120572119895119896

= 119878119895119896

((119883119901

119895sdot 119901119901) 119901119891minus 119883119891

119895)

((119883119901

119896sdot 119901119901) 119901119891minus 119883119891

119896)

119883119891

119896

119883119891

119895

(28)


lim119901119901119901119891rarr0

120572119895119896

= 119878119895119896 (29)










119904is slightly












4 ethanol








(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)



119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)




1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)


1199091015840

















(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












119862119894= 119862119867

119894+ 119862119871

119894= 119870119867

119894sdot 119901119894+

1198621198711015840

119894119887119901119894

1 + 119887119901119894

(25)



119870119867



1015840

119894the


119878119875

119895119896=

119875119895

119875119896

= 119878119863

119895119896sdot 119878119896

119895119896 (26)

The selectivity 119878119901119895119896


120572119895119896

=

119883119901

119895

119883119891

119895

119883119891

119896

119883119901

119896

=

119883119901

119895sdot (1 minus 119883

119891

119895)

119883119891

119895sdot (1 minus 119883

119901

119895)

(27)


120572119895119896

= 119878119895119896

((119883119901

119895sdot 119901119901) 119901119891minus 119883119891

119895)

((119883119901

119896sdot 119901119901) 119901119891minus 119883119891

119896)

119883119891

119896

119883119891

119895

(28)


lim119901119901119901119891rarr0

120572119895119896

= 119878119895119896 (29)










119904is slightly












4 ethanol








(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)



119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)




1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)


1199091015840

















(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











(119909)

119878 =

119909

1199090

997888rarr 119878red =119877air119877gas

ge 1

119878ox =119877gas

119877airge 1

(30)



119877119894= (1 minus

119888119901

119894

119888119891

119894

) = (1 minus

119878119901

119894minus 1

119878119891

119894minus 1

)

⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟⏟

MOS

mit 119877119894=

1

3

3

sum

119894=1

119877119894

(31)




1198761199091015840 (1199011015840

119894) = (

(1119899)sum119899

119896=11199091015840

119896

1199091015840

max

100381610038161003816100381610038161003816100381610038161003816

119901119894

) sdot 100 (32)


1199091015840

















(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










(A)

(B)

(C)

(D)



Polymer membrane

Curing

Polymer fixation

Id 64 bzw 32mm

EPO-TEK H70E

2hrs80∘C

(a)

PTFE

PI

PEEK

(b)


Perm

eate

Chamber A Chamber B

MOS-andorTRH-sensor

on TO-39 header

Feed

EPDM sealing

PTFE sealing

Polymer support





4(1000 ppm) ethanol


4 Results


2








2 ethanol acetone





Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CC

H H

HHn

lowast lowastPE

HDPE

LDPE

(b)


4 500 ppm



2is only minimal



1












Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Membrane Sensor H2

CO CH4


R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

CH

CH

n

n

lowast lowast

lowast lowastCH2

CH2

CH3

CH3

CH3

HDPE

PP

PMP

(b)





1











t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation














t (min)0 100 200 300 400 500 600


ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(a)


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221

minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)

(b)



2groups they lead


2-)







2-) in PES






R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy


MOS (SnO2Pd)

(a)

n

lowast

lowastCH3

CH3

O

O

O

n

lowast lowastO O C

O

n

lowast lowastS

O

O

O

PC

PEEK

PES

(b)




R(Ω

)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

n

lowast lowast

O O

OO

nlowast

lowast

O

O

OO

PET

PEN

(b)





2groups Unlike PC





(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










(Ω)

1M

100k

10k

1k

100

t (min)0 50 100 150 200 250 300 350 400 450 500 550

150

ppm

H2

30

ppm

CO

1000

ppm

CH4

500

ppm

etha

nol

500

ppm

acet

one

25pp

m ac

etal

dehy

de


MOS (SnO2Pd)

(a)

H

n

lowastlowast

O

N

nlowast

lowast

O

O

O

O

O

N

N

Cnlowast

lowast

CH3

OO

OO

O

O

N

N

H3C

PA6

PI

PEI

(b)








4














2 30 ppm





Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Membrane Sensor H2

CO CH4



Membrane Sensor H2

CO CH4







4in the H

2-selective




4can be






2 CO CH


2

and CO2




R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










R(Ω

)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k900k850k

800k

750k

700k

t (min)150 200 250


MOS (SnO2Pd)

(a)R

(Ω)

10M

1M

100k

t (min)0 50 100 150 200 250 300 350 400

1pp

mN

O2

100

ppm

CO

3000

ppm

CH4 1vol CO2

R(Ω

)

950k

900k

850k

800k

t (min)150 200 250


MOS (SnO2Pd)

(b)



2and 1 vol CO


t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(a)

t (min)0 100 200 300 400 500 600

ΔBfeed

ΔAfeed

HYT221minus2

0

2

4

6

8

10

12

14

16

120588w

(gm

3)


(b)







2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












2




3) [61]



NO2 andCO



2 The highest


2 the height of the


4in the absence



2 CO CH

4 ethanol acetone







References



































095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation





























095Rh005

O3catalytic filter






2rdquo











3(BTC)
















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation














































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Research Article Organic Membranes for Selectivity...

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Transcript of Research Article Organic Membranes for Selectivity...