Dr. Junhang Dong (PI) Dr. Robert Lee (Manager) Mr. Liangxiong Li (Ph.D. student) Dr. Xuehong Gu...
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Transcript of Dr. Junhang Dong (PI) Dr. Robert Lee (Manager) Mr. Liangxiong Li (Ph.D. student) Dr. Xuehong Gu...
Dr. Junhang Dong (PI)
Dr. Robert Lee (Manager)
Mr. Liangxiong Li (Ph.D. student)
Dr. Xuehong Gu (Postdoc)
Report of Research Progress In 2003
Petroleum Recovery Research Center (PRRC)
New Mexico Institute of Mining and Technology
Patent Pending
ACKNOWLEDGEMENTS
New Mexico Tech: the president’s office provided $100K for equipment
DOE: funding through the NPTO in NETL under contract No. DE-FC26-00BC15326
Petroleum Recovery Research Center, A Division of the New Mexico Institute of Mining and
TechnologyPRRC
PRRC/NM Tech:Delivery is our Job #1
• A research arm of New Mexico oil and gas industry, only for oil and gas industry, dedicated to industry’s interests alone.
• PRRC/NM Tech research directions are governed by its advisory board members including:(1) New Mexico Oil & Gas Association (NMOGA)(2) Independent Producers Association (IPANM) (3) New Mexico Oil Conservation Division (NMOCD)(4) New Mexico State Land Office (NMSLO)
• NMOGA, IPANM, NMOCD, and SLO are policy-making organizations but PRRC/NM Tech is for research only.
Acknowledgement
NPTO/NETL/DOE State of New Mexico (Governor, Senators, Representatives)NM Tech President Office (Dr. Lopez)NMOGA, IPANM, NMOCD, and SLO(Bob Gallagher, Deborah Seligman, Jeff Harvard,
Tucker Bayless, Lori Wrotenbery, and Jami Baily)
PRRC Separation group members:Dr. Junhang Dong (group leader)Ashlee RyanXuehong GuAditi MajumdarKatsuya SugimotoAmber WoodyattLiangxiong Li
• PART I: Desalination of Produced Water– Supported clay membranes
– Zeolite membranes
• PART II: CO2 Separation By Clay Membranes– Development of PILC membranes for high temperature
CO2 capture
– Preliminary results on plain clay membranes
• PART III: Nonoxidative CH4 Conversion– Concept of the new catalytic membrane
– Proof of concept
Presentation Plan
PART I
Desalination of Produced Water
• Supported Clay Membranes
• Zeolite Membranes
Stainless steel mold for mounting the compacted clay membrane
Schematic showing the mechanism of desalination on clay membranes
1. Compacted bentonite membranes as thin as 60m were prepared.
2. Desalination was demonstrated on compacted clay membranes.
3. Problems: — Not suitable for produced water due to the rapidly diminishing ion rejection with increasing ion concentration. — Too brittle to be practical. — Extremely low flux due to thickness.
• For practical applications, supported, thin membranes must be developed
Previous Work
Refining of clay nanoparticles (dia.< 50 nm) from commercial powders
1. Dispersion2. Washing & centrifuging3. Freeze drying
Redispersion of nanoparticles
PVA Binder
pH control
Colloidal suspension for membrane coating: 0.7 wt% clay + 0.05 wt% PVA pH = ~7.5
Membrane Synthesis Route
Dip-coating or slip-casting
Controlled drying:40oC, ~60%RH
Calcination: 0.5oC/min; 450 - 600oC
SEM Pictures of the Alumina-Supported Clay Membrane
Cross-section Surface
Membrane thickness = 2 ~ 3 mBET surface area = ~ 60 m2g-1
Mesopore volume = ~ 0.075 cm3g-1
Mean pore size = 5 ~ 9 nm
TEM image of the clay membraneparticle size: dia. < 50 nm
0 10 20 30 40 502
Rel
ativ
e In
ten
sity
A
B
C
XRD patterns. A – -alumina substrate, B – refined powders fired at 600°C, C – -alumina-supported clay membrane
fired at 600°C
Material Characterizations
Water bottle
Sample collector
Feed outlet
Feed tank
Water analysis
Membrane cell
Feed pressure control
Flow control valve
Feed solution
High pressure N2 cylinder
The RO Desalination System
The cell
The I.C.
Calcination
conditions
Thickness,
m pf
*, MPa Flux, mol·m-2·h-1 r, %
450oC for 3h ~2.0 0.41 34.11 4.5
500C for 3h ~2.0 0.82 8.33 44.5
600C for 3h ~2.0 No flux under feed pressure of up to 1.03 MPa
700C for 3h ~2.0 No flux under feed pressure of up to 1.03 MPa
Results of RO Desalination for a 0.1M NaCl Solution
%100)(
)()(
feeds
permsfeeds
C
CCrRejection:
pf is the applied pressure.
Mem* Solution
m
Pf
MPa
Flux
mol·m-2·h-1
Permeance
mol·m-2·kPa-1·h-1
Permeability
mol·m-1·kPa-1·h-1 r, % Ref.
CP 0.60M NaCl 2200 27.4 0.088 3.21x10-6 7.06x10-8 60.0 ( 2 )
CP 0.8M
NaCl+0.15M CaCl2
5000 13.9 0.452 3.25x10-5 1.62x10-7 60.0 ( 5 )
CP 5.04M NaCl
+ 0.45M CaCl2
16,000 13.8 0.275 1.99x10-5 3.19x10-7 25.0 ( 6 )
CP 0.10M NaCl 60 5.2 7.22 1.38x10-3 8.33x10-8 62.9 ( 7 )
SP 0.10M NaCl 2 0.82 5.5 6.71x10-3 1.34x10-8 44.5 This study
Comparison Between Supported Membrane and Compacted Membranes
* CP – compacted membrane; SP – supported membrane
ab PP
pfa pp
F
P
FP
tA
QF
m
w
Mw
RT
C
C
C
C
feeds
s
perms
s
100100
1. Supported mesoporous clay membranes have been synthesized for the first time
2. The supported thin membranes is superior to the compacted membrane:
- Mechanical strength- Rejection comparable to the compacted - High flux and low operation pressure
3. Clay membranes are less likely to succeed in the real world- Structurally unstable in aqueous conditions (swelling)- Rejection lost in high concentration solution
4. Potentially excellent for CO2 and other gas separation
5. Need new membrane with separation mechanisms not inhibited by high concentration
Conclusions for Clay Membranes
• Separation mechanisms
– Molecular sieving
– Selective adsorption
– Diffusion
• Current synthesis methods– In situ crystallization
– Seeding/secondary growth
– Vapor-phase transport
• Extensively studied for gas separations
• Not explored for RO desalination
Film formation
Nucleation Crystal growth
Zeolite Membranes
MFI dp: 5.6Å
• Computer simulation showed 100% Na+ rejection on zeolite-A perfect membranes• RO test for EtOH/water separation on A-type zeolite membrane
Rejection of hydrated ion by molecular sieving effect through intracrystal pores
Two types of pores in polycrystalline membranes:
(1) Intracrystal pore (zeolitic) and (2) intercrystal pores
Rejection by overlapping double layers in intercrystal pores
5 m
MFI membrane synthesized by seeding-secondary growth. No template used
MFI membrane synthesized by in situ crystallization method (templated).
MFI Membranes Synthesized by Different Methods
0 100 200 300 400 500
Temperature, C
-2.5
-1.5
-1.0
-0.5
0.5
1.0
1.5
-2.0
0.0
Th
erm
al e
xpan
sio
n/c
on
trac
tio
n r
atio
, %
o
MFI zeolite on alum ina support
MFI zeolite on YZ support
MFI zeolite powder
Fitted line
a
a
a
a 25 C after template rem ovalo
Mismatch of thermal expansion between the
MFI layer and substrates
Microstructure Evolution for Supported MFI Membranes During Template Removal
Strong bonding between zeolite layer and support formed prior to H.T. (e.g.
on alumina)
Illustration of an intercrystal pore
0 20 40 60 80 100Time, h
0.15
0.25
0.35
0.10
0.20
0.30
0.40
Flu
x, k
g m
h
-10
10
20
30
50
60
70
0
40
80
Rej
ecti
on
(R
), %
-2
-1
Flux
Rejection
Water Flux and Na+ Rejection as Functions of OR Operation Time for the 0.1M NaCl Solution
Flux 50% higher than supported clay membranesRejection almost twice as high as that on supported clay membranes
25 75 1250 50 100 150Time, h
-20
-10
10
20
30
50
60
70
90
100
0
40
80
Rej
ecti
on
(R
), %
Na
K
NH
Ca
Mg+
+
+4
2+
2+
Ion Rejection as a Function of Operation Time for a Multicomponent Feed Solution
Feed composition
NaCl 0.1M
KCl 0.1M
NH4Cl 0.1M
CaCl2 0.1M
MgCl2 0.1M
(Total ~ 80,000ppm)
Overall rejection (stabilized) ~ 80%Stabilized water flux ~ 0.6 - 0.12 kg/m2 h
New Synthesis Method: Wet Gel VPT-Seeding and Secondary Growth
5 m
Step 2Secondary growth
Step 1 Wet gel VPT
1. First demonstration of RO desalination on zeolite membranes
2. Highly stable structure and unique separation mechanism- Can handle high concentration (produced water)- Can tolerate organic materials - High rejection and flux
3. Issues that need further investigation- Zeolite with different pore size- Minimize intercrystal pores and thickness- Better understanding of separation mechanism and effects of
operation conditions- Tests with real produced water- Finding cheap way to fabricate membrane
4. Promising results obtained on a new synthesis method of VPT and secondary growth
- Better reproducibilty- Higher success ratio (low cost)
Summary for Zeolite Membranes
PART II
CO2 Separation with Clay Membranes
• A new type of PILC membrane for high temperature CO2 separation
• Preliminary results on plain bentonite membranes
• High temperature CO2 capture is the key to realizing CO2 sequestration strategies.
• Current industrial methods are not economical.
• Membrane approach is energy-saving, thus the future direction.
- Polymeric membrane for T<150oC
- Organic-inorganic composite membrane for
T<300oC but has low permeability
- Ceramic membranes for T>300oC but has very low
selectivity, S<2
• Challenge: developing highly CO2-selective, porous inorganic membranes
Current Status
ASSUMPTIONS:
i) Chemisorption of CO2 and negligible N2 adsorption;
ii) Single layer adsorption, = Kp.
iii) CO2 transport via surface diffusion with minimized Knudsen flow
2
2
)(
)(
NK
COKsc P
PPS
CO2 permeability of surface diffusion (Ps)
Selectivity (Sc) of CO2/N2 for a 50/50 feed
WK M
RT
RT
rP
8
3
2
Permeability of Knudsen diffusion (PK)
RT
aQ
rANKDP c
As
)1(exp
200
Requirements for A Porous Ceramic Membrane — Theoretical Analysis
THEORETICAL MODEL
-alumina (A) MgO/-alumina (B)
d/dp (Pa-1) 8x10-7 9x10-7
-Qc (kJ mol-1) 45 56
T (K) 543 573
Ds (kJ mol-1 K-1) 1.8x10-8 8.1x10-9
Ps (mol m-1 s-1 Pa-1) 2.7x10-11 1.2x10-11
(PK)CO2 (mol m-1 s-1 Pa-1) 5.8x10-12 5.6x10-12
(PK)N2 (mol m-1 s-1 Pa-1) 7.3x10-12 7.1x10-12
CO2 permeance (PCO2) (mol m-2 s-1 Pa-1) 3.28x10-6 1.76x10-6
Selectivity SCO2/N2 for a 50/50 feed 4.5 2.5
Calculated CO2/N2 separation on mesoporous membranes (dp=10nm, thickness=10m) — influence of adsorbing strength
(assuming negligible viscous flow)
* Based on data of Horiuchi et al., 1996.
Requirements for A Porous Ceramic Membrane
Ideal scenario of adsorption-diffusion membrane separation
(1) Pore diameter < 1 nm to inhibit Knudsen diffusion and increase the selectivity.
(2) Optimal CO2 adsorbing strength to maximize the permeability and selectivity.
(3) Large microporous surface area to enhance the surface diffusion permeability
OLIGOMERIC HYDROXY METAL CATIONS e.g. [Al13O4(OH)24(H2O)12]
7+ (Vercauteren et al., 1996)
CLAY SHEETS (LAYERS)
DRYING AND RE-CALCINATION
METAL OXIDE PILLARS ION XECHANGE
The Proposed Microporous PILC Membrane
(1) Established membrane synthesis method.
(2) Controllable pore size between 4Å to 30Å by adjusting pillaring materials.
(3) Adjustable surface adsorbing strength, from physical adsorption to chemisorption, by ion-doping and pillaring.
Surface modification by alkali metal oxides
Test of CO2 Separation on Plain Clay Membrane
1 3 50 2 4 6Perm eation tim e, h
5.0
15.0
25.0
0.0
10.0
20.0
30.0
Sep
arat
ion
fea
cto
r fo
r N
2 o
ver
CO
2 25 C
100 C
Knudsen factor = 1.25
o
o
Separation of a 50(CO2)/50(N2) mixture on the mesoporous bentonite membrane
(1) Weak adsorption — adsorption heat: 15 - 33
kJ/mol.
(2) Mesoporous (6-9nm) — Knudsen flow is significant.
(3) Adsorption of CO2 on the pore surface slows down the transport of CO2.
(4) Membrane in good quality — indicated by selectivity greater than Knudsen factor.
(5) Microporous PILC membranes needs to be developed.
PART III
Novel Catalytic Membrane for CH4 Conversion to C2+ and H2
• Concept
• Catalytic membranes synthesis
• Preliminary results
Background
1. DOE and the energy industry seek more efficient and cleaner new technology for natural gas conversion to H2 and C2+
2. Oxidative membrane reactor — membrane instability, low conversion at high selectivity; emission of CO2, high reaction temperature >850oC …
3. Direct CH4 conversionAdvantages:
- 100% selectivity - Low operation temperature, 250~450oC- Zero CO2 emission …
Disadvantages:- Thermodynamically limited two-step process- Endothermic and very low equilibrium conversion
Principle of Nonoxidative CH4 Conversion
A new membrane reactor must be developed to overcome the two-step limitation and the thermodynamic barrier
Pulse Feed Reactor
Illustration of continuous operation of single-step CH4 conversion through a zeolitic channel
Mechanism of the New Catalytic Membrane
Feed side Membrane Permeate side
MS
Reactor
The Experimental System
Pt-Co/NaY
NaY only
Ionic and Catalytic Membrane Characterization Apparatus
0 10 20 30t(m in )
0
1E-008
2E-008
3E-008
4E-008
5E-008
AM
PS
2E-010
4E-010
6E-010
8E-010
AM
PS
m /e=44
m /e=16
A
0 10 20 30t(m in )
0
1E-008
2E-008
3E-008
4E-008
5E-008
AM
PS
0
2E-010
4E-010
6E-010
AM
PS
m /e=44
m /e=16
B
Proof of Concept
Results of CH4 conversion on Pt-Co/NaY Membrane
C3H8
CH4
CH4
A: The main product of conversion on the Pt-Co/NaY membrane is C3H8, which accounts for ~80% of the total C2+. Membrane deactivated in ten min due to excessive carbon formation on the catalyst surface — significantly longer than in pulse feed reactor (<one min).
B: On a NaY membrane without catalyst under identical conditions. No intensity change at m/e=44 (C3H8) was observed, proving that C3H8 was generated in a single-step, continuous manner on the Pt-Co/NaY membrane.
Nonoxidative In Situ Membrane Regeneration
0 40 80 120 160t(m in)
0
2E -008
4E -008
6E -008
0
2E -011
4E -011
6E -011
8E -011
0
5E -010
1E -009
1 .5E -009
AM
PS
0
1E -011
2E -011
3E -011
0
1E -011
2E -011
3E -011m /e=72 (C 5H 12)
m /e=58 (C 4H 10)
m /e= 44 (C 3H 8)
m /e=30 (C 2H 6)
m /e=16 (C H 4)
1. Minor increases in the intensities of m/e = 30 (C2H6), 44 (C3H8), 58 (C4H10), 72 (C5H12) were observed within the first 10 minutes after introducing CH4 into the feed.
2. In about 120 minutes after introducing CH4, significant increases in conversion rate of m/e = 30 (C2H6), 44 (C3H8), 58 (C4H10), 72 (C5H12).
3. The results suggest that (i) the carbon deposit was in reactive forms; (ii) activation of Co might take longer time than Pt; and (iii) the Pt-Co bimetallic catalyst had higher catalytic activity than single metal (Pt).
4. Deactivation significantly reduced.
Using H2 to rehydrogenate reactive carbon deposit
• The new type of metal-loaded zeolite membrane, e.g. Pt- Co/NaY membranes, can overcome the two-step limitation of nonoxidative CH4 conversion into C2+ and H2.
• Other metal-loaded microporous membranes, e.g. microporous silica membranes, microporous pillared clay membranes, and microporous carbon membranes, etc., may also be used for such purpose.
• A breakthrough in the area of nonoxidative CH4 conversion.
• This invention may lead to a completely new technology for efficient conversion of natural gas into more valuable higher hydrocarbons and hydrogen.
Summary for PART III
First realization of direct conversion of CH4 into C2+ and H2 by Continuous Operation
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