INDUSTRIAL GAS

INDUSTRIAL GASESChemical Process IndustryWhat are industrial gases?Industrial gases are a group of gases that are specifically manufactured for use in a wide range of industries, which include oil and gas, petrochemicals, chemicals, power, mining, steelmaking, metals, environmental protection, medicine, pharmaceuticals, biotechnology, food, water, fertilizers, nuclear power, electronics and aerospace.

What defines an industrial gas?Industrial gas is a group of materials that are specifically manufactured for use inindustryand are also gaseous at ambient temperature and pressure. They arechemicalswhich can be anelemental gasor achemical compoundthat is eitherorganicorinorganic, and tend to be lowmolecular weightmolecules. They could also be amixtureof individual gases. They have value as a chemical; whether as afeedstock, in process enhancement, as a useful end product, or for a particular use; as opposed to having value as a "simple"fuel.What defines an industrial gas?The term industrial gasesis sometimes narrowly defined as just the major gases sold, which are: nitrogen, oxygen, carbon dioxide, argon, hydrogen, acetylene and helium.Many names are given to gases outside of this main list by the different industrial gas companies, but generally the gases fall into the categories "specialty gases", medical gases, fuel gases or refrigerant gases. However gases can also be known by their uses or industries that they serve, hence "welding gases" or "breathing gases", etc.; or by their source, as in "air gases"; or by their mode of supply as in "packaged gases". The major gases might also be termed "bulk gases" or "tonnage gases".What defines an industrial gas?In principle any gas or gas mixture sold by the "industrial gases industry" probably has some industrial use and might be termed an "industrial gas". In practice, "industrial gases" are likely to be a pure compound or precise mixture, packaged or in small quantities, but with highpurityor tailored to a specific use (e.g.oxyacetylene). Lists of the more significant gases are listed in "The Gases" below.There are cases when a gas is not usually termed an "industrial gas"; principally where the gas isprocessedfor later use of itsenergyrather thanmanufacturedfor use as a chemical substance or preparation.Theoil and gasindustry is seen as distinct. So, whilst it is true that natural gas is a "gas" used in "industry" - often as a fuel, sometimes as a feedstock, and in this generic sense is an "industrial gas"; this term is not generally used by industrial enterprises forhydrocarbonsproduced by thepetroleum industrydirectly fromnatural resourcesor in anoil refinery.What defines an industrial gas?Thepetrochemicalindustry is also seen as distinct. So petrochemicals (chemicals derived frompetroleum) such asethyleneare also generally not described as "industrial gases".Sometimes the chemical industry is thought of as distinct from industrial gases; so materials such as ammonia and chlorine might be considered "chemicals" (especially if supplied as a liquid) instead of or sometimes as well as "industrial gases".These demarcations are based on perceived boundaries of these industries (although in practice there is some overlap), and an exact scientific definition is difficult. To illustrate "overlap" between industries:

What defines an industrial gas?Manufacturedfuel gas(such astown gas) would historically have been considered an industrial gas.Syngasis often considered to be a petrochemical; although its production is a core industrial gases technology. Similarly, projects harnessingLandfill gasorbiogas,Waste-to-energyschemes, as well as Hydrogen Production all exhibit overlapping technologies.Helium is an industrial gas, even though its source is from natural gas processing.Any gas is likely to be considered an industrial gas if it is put in a gas cylinder (except perhaps if it is used as a fuel)Propane would be considered an industrial gas when used as a refrigerant, but not when used as a refrigerant in LNG production, even though this is an overlapping technology.

Where do they come from?

Oxygen, nitrogen, argon, xenon, neon and krypton are produced from the air. Carbon dioxide is primarily collected from the exhaust of industrial operations and cleaned. In some cases it is also produced from natural underground sources. Hydrogen and acetylene are produced chemically. Helium is extracted from underground sources.

8Who needs the industrial gases?

Industrial gases are used in a variety of purity grades and for a wide range of purposes. Including as food gases and medical gases. Industrial gases can make production processes safer and more cost-effective and improve product quality. They often contribute to environmental protection. Some processes and applications would even be inconceivable without the chemical processes of gases. Typical user sectors include the automotive industry, the steel industry, environmental engineering, food and beverages, construction, metallurgy, glass and ceramics, medicine and pharmaceuticals, the chemical industry, and research and development.

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The image Breakfast illustrates the use of nitrogen (N2) for, among other things, the preparation of finely ground spices or the optimal packaging of cheese. Carbon dioxide (CO2) is used, for example, to fertilise vegetables, to chill dough or to decaffeinate coffee and of course as sparkling carbon dioxide in beverages. Oxygen (O2) is used in the production of glass, and ozone (O3) helps bleach paper in an eco-friendly way.

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CARBON DIOXIDE

PROPERTIESChemical formula: CO2Molecular weight: 44.01 g/molBoiling point: -78.5 oCMelting point: -55.6 oCDensity: 1.977

PROPERTIESColourlessOdorlessSoluble in water, ethanol, and acetone

PROPERTIESLinear covalent moleculeAcidic oxide CO2 + H2O ==> H2CO3CO2 + NaOH ==> NaHCO3NaHCO3 + NaOH ==> Na2CO3 + H2O

USESLarge quantities of solid CO2 (i.e. in the form of dry ice) are used in processes requiring large scale refrigerationCO2 reduces meat and food bacteria spoilage

USESuse in carbonation of beveragestreatment of drinking waterwastewater neutralizationgreenhouse fertilizer coolantcleaning agent (as dry ice); Transport refrigerant for food refrigerationfirefightingpaper recycling

USESCarbon dioxide also plays an important role in Photosynthesis.

Plants require carbon dioxide to conduct photosynthesis, and greenhouses may enrich their atmospheres with additional CO2 to boost plant growth.

MANUFACTURE OF CO2 Sources of CO2 for commercial production - recovery from synthesis gas in ammonia production - recovery as a by-product in the production of SNG - recovery from the production of ethanol by fermentation - recovery from natural wells

MANUFACTURE OF CO2 CO2 from the combustion of fuel oil in aboiler plant generating the required steam

- oil, natural gas, or coke is burned, giving heat for 1380 kPa steam and furnishing 10 to 15% CO2 at 345oC - flue gas cooled, purified, and washed by passing through two water scrubbers

MANUFACTURE OF CO2 - CO2 is removed by countercurrent selective absorption into an aqueous solution of ethanolamines - CO2 ethanolamine solution is pumped to a steam-heated reactivator - CO2 and steam leave the top of the reactivator passing through a CO2 cooler to condense the steam, which returns to the tower as reflux

MANUFACTURE OF CO2 - CO2 at about 200 kPa is purified from traces of H2S and amines in a permanganate scrubber and dried - CO2 is compressed, cooled, and liquefied

MANUFACTURE OF CO2 For dry ice - liquid CO2 is reduced to atm with consequent partial solidification - evaporated gas returns through the precooler and is recirculated with recompression and recooling of CO2 - CO2 snow is compressed to form a cake - Dry ice cakes are sawed to 25-cm cubes of approx. 23-kg weight

FLOWCHART FOR CO2 FROM FUEL OIL OR NATURAL GAS

MANUFACTURE OF CO2 Fermentation industry is another source of CO2

FLOWCHART FOR FERMENTATION CO2 PURIFICATION

INDUSTRIAL GASHYDROGEN PRODUCTIONBrief History on Hydrogen1520-The first discovery of hydrogen gas by Swiss Alchemist Philippus Aureolus Paracelsus1766-Hydrogen was first identified as a distinct element by British scientist Henry Cavendish1788-French Chemist Antoine Lavoisier gave hydrogen its name. hydro and genes, meaning water and born of1800-English scientists William Nicholson and Sir Anthony Carlisle discovered electrolysis

1920-The first commercial technology the electrolysis of water to produce pure hydrogen1959-Francis T. Bacon built the first practical hydrogen-air fuel cell Bacon Cell-Harry Karl Ihrig demonstrated the first fuel cell vehicle: a 20-hp tractor1960-The industrial production of hydrogen shifted slowly towards a fossil-based feedstock1990-The worlds first solar powered hydrogen production plant at Solar-Wasserstoff-Bayern, a research and testing facility in southern Germany1520-he first described a gaseous substance arising as iron was dissolved in sulfuric acid-he described this substance as an air which bursts forth like the wind

1766-he separated hydrogen gas by reacting zinc metal with hydrochloric acid-he applied a spark to hydrogen gas yielding water (discovery that water is made up of hydrogen and oxygen)

1800-they discovered that applying electric current to water produced hydrogen and oxygen gases later termed as electrolysis

1959-Bacon cell is 5-kW system that powered a welding machine-Hydrogen Fuel Cells have been used to generate on-board electricity, heat and water for astronauts aboard the famous Apollo spacecraft and all subsequent space shuttle missions

1960-fossil-based feedstock is the mains ource of hydrogen production today

27Hydrogen (H2)Colorless, odorless, tasteless, flammable and nontoxic gas at atmospheric temperatures and pressuresThe most abundant element in the universeNot an energy source, but is an energy vector or carrier

Hydrogen is not an energy source, but is an energy vector or carrier. This means that it has to be produced from one of the primary energy sources: fossil fuels, nuclear, solar, wind, biomass, hydro, geothermal and urban waste resources. All the energy we use, including hydrogen, must be produced from one of these three primary energy resources.

28Hydrogen Application and UsesHydrogen Application and UsesMetalsChemicals, Pharmaceuticals and PetroleumGlass and CeramicsFood and BeveragesElectronicsMiscellaneous

Metals-Hydrogen is mixed with inert gases to obtain a reducing atmosphere, which is required for many applications in the metallurgical industry, such as heat treating steel and welding. It is often used in annealing stainless steel alloys, magnetic steel alloys, sintering and copper brazing

Chemicals, Pharmaceuticals and Petroleum-Hydrogen is used in large quantities as a raw material in the chemical synthesis of ammonia, methanol, hydrogen peroxide, polymers, and solvents-In refineries, it is used to remove the sulfur that is contained in crude oil. Hydrogen is catalytically combined with various intermediate processing streams and is used, in conjunction with catalytic cracking operations, to convert heavy and unsaturated compounds to lighter and more stable compounds-The pharmaceutical industry uses hydrogen to manufacture vitamins and other pharmaceutical products-Large quantities of hydrogen are used to purify gases (eg. Argon) that contain trace amounts of oxygen, using catalytic combination of the oxygen and hydrogen followed by removal of the resulting water-More than a quarter of the world production of hydrogen is used in oil refineries primarily to separate sulfur, nitrogen and metallic impurities, as well as for the transformation of hydrocarbons-Hydrogen are also in chemistry for the synthesis of intermediate products such as amines and hydrogen-superoxides-Hydrogen can also harden the comestible fats

Glass and Ceramics-In float glass manufacturing, hydrogen is required to prevent oxidation of the large tin bath

Food and Beverages-It is used to hydrogenate unsaturated fatty acids in animal and vegetable oils, producing solid fats for margarine and other food products

Electronics-Hydrogen is used as a carrier gas for such active trace elements as arsine and phospine in the manufacture of semi-conducting layers in integrated circuits-Hydrogen in electronics avoid oxidation of semiconductors-Hydrogen is used for the welding and cutting of materials as its combustion with oxygen occurs around 3000degC-Very important application of hydrogen is in metal-hydride batteries based on LaNi5Hx, which already now have conquered an importatnt part of the multi-billion rechargeable battery market. Their superior stored energy to weight ratio makes them especially attractive for mobile telephones

Miscellaneous-Generators in large power plants are often cooled with hydrogen, since the gas processes high thermal conductivity and offers low friction resistance-liquid hydrogen is used as a rocket fuel-The nuclear fuel industry uses hydrogen as a protective atmosphere in the fabrication of fuel rods

30Feedstock and Process TechnologiesFeedstockFossil ResourcesNatural GasCoalRenewable ResourcesBiomassWater with input from renewable energy sourcesRenewable Energy SourcesSunlightWindWave or Hydro-Power

Reforming of Natural GasGasification of Coal and BiomassSplitting of Water by:Water-electrolysisPhoto-electrolysis (Photolysis)Photo-biological Production (biophotolysis)High Temperature DecompositionProcess Technologies32

Fossil resources:-natural gas-coal

Renewable Resources:-biomass-water with input from renewable energy sources

*Renewable Energy sources-sunlight-wind-wave or hydro-power33

34Thermochemical Sulfur-Iodine Process

High-Temperature DecompositionHigh-temperature splitting of water occurs at about 3000 0C. At this temperature, 10% of the water is decomposed and the remaining 90% can be recycled.To reduce the temperature, other processes for high temperature splitting of water have been suggested:Thermo-chemical cyclesHybrid systems coupling thermal decomposition and electrolytic decompositionDirect catalytic decomposition of water with separation via a ceramic membrane (thermo-physic cycle)Plasma-chemical decomposition of water in a double-stage CO2 cycleHigh-Temperature Decomposition-aka Thermal Decomposition-aka Thermolysis-a chemical decomposition caused by heat-decomposition temperature of a substance is the temperature at which the substance chemically decomposes-reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition

*For these processes, efficiencies above 50% can be expected and could possibly lead to a major decrease of hydrogen production costs.36Thermo-chemical Water Splitting CyclesThe conversion of water into hydrogen and oxygen by a series of thermally driven chemical reactionsThey were extensively studied in the late 1970s and 1980s, but have been of little interest in the past 10 years

*An example of a thermo-chemical process is the Sulfur-Iodine CycleSulfur-Iodine Cycle Reactions

H2SO4 SO2 + H2O + O2I2 + SO2 + 2H2O H2SO4 + 2HI2HI I2 + H2

Overall BalanceH2O H2 + O2

3 sections:Section 1-Prime or Bunsen ReactionI2 + SO2 + 2H2O H2SO4 + 2HI

Section 2-Sulfuric Acid DecompositionH2SO4 SO2 + H2O + O2

Section 3-Hydrogen Iodide Decomposition2HI I2 + H2

High predicted efficiency: ~50% at 900 degC39Section 1 Bunsen Reaction and Chemical recycle

Section 2 Sulfuric Acid Concentration and Decomposition

Section 3 Hydrogen Iodide Decomposition

High recycle to Section 1-5 to 1 recycle of HI-4~5 moles H2O & I2 per mole HI

Efficiency52% at 900 degC42Thermo-chemical Water Splitting (Sodium-Iodide Cycle)AdvantagesNet plant efficiencies up to ~50%Products are only Oxygen and HydrogenEndothermicAll reagents used are recycled; no effluentsNeeds least development among all other thermochemical cyclesDisadvantagesHigh Efficiency is attained at high temperature, 8000C *Still a developing technology43

Peak Process Temperature (deg. C)Environmental Issues and Concerns

473 Different Approaches to Alleviating the Problems Associated with the Energy Hunger of HumanityPreventing the cause of global warming to escape into the atmosphere (i.e. CO2 sequestration), known as the clean fossil hydrogen optionA drastic efficiency increase in energy usageA transition from fossil fuels to sustainable, carbon dioxide neutral ones*Hydrogen can reduce CO2 emissions and dependence on fossil fuels-no greenhouse gases-Hydrogen produces only water as the waste product-In a fuel cell, hydrogen can get twice the efficiency as a gasoline engine

Hindrance-where to get hydrogen-hydrogen is an energy carrier, not an energy source-energy is required to separate H from oxygen or carbon48STEAM REFORMATION

STEAM REFORMATIONSteam reforming or Fossil fuel reformingis a process used toproduce hydrogen fromhydrocarbonfuels such asnatural gas and coals.

a process used toproduce hydrogen fromhydrocarbonfuels such asnatural gas and coalsachieved in a processing device called a reformer which reacts steam at high temperature with the fossil fuel

Figure 1, Schematic of SMR Process Showing Heat and Materials Integration

50Steam Reformation: Flow Diagram

Hydrogen Production via Steam ReformationFeedstock PurificationSteam ReformationGas Conversion-High Temperature Shift Conversion-Low Temperature Shift ConversionPurificationPollution Control TechnologiesFeedstock PurificationRemoval of poisons such as sulphur and chloride to maximize the life of the downstream steam reforming and other catalystsThe best way to remove sulphur compounds is to convert the organic sulphur species to H2S over a hydrodesulphurization catalystC2H5SH + H2C2H6+ H2SThe next step is sulphur removal with an absorbent

53Catalyst-Molybdenum disulfide together with smaller amounts of other metals -Also converts any organic-chloride species to give HCl and also acts as an absorbent for most problematic metal speciesFeedstock Purification

Steam ReformingCH4+ H2O CO + 3 H2CxHy + H2O = x CO + (x + 0.5y) H27001100CHighly endothermicThe reaction takes place across a nickel catalyst packed in tubes in a fired furnaceAn excess of steam is used to promote the reforming reaction and avoid carbon deposition on the catalyst.

Shift ConversionCO + H2O CO2 + H2Hreac=41.16kJmol1at298.15KHigh Temperature Shift Conversion (water-gas shift reaction)Low Temperature Shift Conversion

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High Temperature Shift ConversionIncreases the hydrogen yield by driving the water-gas shift reaction to the rightAbout 350C (662F) inlet temperature Lowers the CO level from 10-15 mol % (dry) to 1-2 mol % (dry)Catalyst: Fe3O4(magnetite)

Low Temperature Shift ConversionEnables increased hydrogen yield by further moving the water-gas shift equilibrium in favour of H2190-210C (374-410F) inlet temperature Lowers the CO level from 1-2 mol % (dry) to 0.1-0.2 mol % (dry) Catalyst: Raney copper catalystProduct PurificationPressure Swing Absorption UnitFour basic process steps: Adsorption Depressurization Regeneration Repressurization99.99% product hydrogen

60Environmental Issues and Concernsthis method of producing hydrogen contributes to global warming unless associated carbon emissions are captured and stored

62Methanationremoves traces of carbon oxides which may affect downstream H2 user plants

CO + 3H2 = CH4 +H2O

CO2 + 4 H2 = 2CH4 + 2H2O

Carbon Capture Methods i.e. Post Combustion, Pre Combustion

WATER ELECTROLYSIS

Thermodynamics

WATER ELECTROLYSISElectrolysisis a method of using adirectelectric current(DC) to drive an otherwise non-spontaneous chemical reaction.Electrolysis of wateris thedecomposition of water(H2O) intooxygen(O2) andhydrogengas (H2) due to anelectric currentbeing passed through the water.ElectrolyzerHydrogen produced via electrolysis can result in zero greenhouse gas emissions, depending on the source of the electricity usedElectrolyzers can be small, appliance-size equipment and well-suited for small-scale distributed hydrogen production. Research is also under way to examine larger-scale electrolysis that could be tied directly to renewable or other non-greenhouse gas emitting electricity production. 66Water Electrolysis: Historysince the early 1900sNicholson and Carlisle were the first to discover the ability of electrolytical water decomposingBy 1902 more than 400 industrial water electrolysis units were in operation and in 1939 the first large water electrolysis plant went into operationIn 1948, the first pressurized industrial electrolyser was manufactured by Zdansky/Lonza.In 1966, the first solid polymer electrolyte system (SPE) was built by General Electric, and in 1972 the first solid oxide water electrolysis unit was developed. 67The minimum necessary cell voltage to start water electrolysis is the reversible (no losses in the process) potential:

n=number of electrons transferred (n=2) F=Faradays constant (F=96487 C/mol)

Alkaline electrolysis-Alkaline electrolysers use an aqueous KOH solution (caustic) as an electrolyte that usually circulates through the electrolytic cells.

Common electrolyte: aqueous potassium hydroxide (KOH) at 30% concentration Operation Conditions: 70-100oC and 1-30bar Can utilize cost effective electrode materials (iron, nickel, nickel compounds) Diaphragm often asbestos Efficiency: 70-80% (based on hydrogen HHV)

Polymer electrolyte membrane (PEM) electrolysisPEM electrolysers require no liquid electrolyte (solid), which simplifies the design significantly.No caustic electrolyte in circulationThe heart of a PEM or SPE electrolyser is a proton exchange membrane (or solid polymer) electrolyte Disadvantage: limited lifetime of the membranes

PEMThe amount of gases produced per unit time is directly related to the current that passes through the electrochemical cellIn pure water at the negatively charged cathode, areductionreaction takes place, with electrons (e) from the cathode being given to hydrogen cations to form hydrogen gas At the positively charged anode, anoxidationreaction occurs, generating oxygen gas and giving electrons to the anode to complete the circuitThe minimum necessary cell voltage is Ecell = 1.21 V

Anode structure: porous titanium and activated by a mixed noble metal oxide catalystCathode structure: porous graphite current collector with either Pt or a mixed oxide as electrocatalystMembrane: Perfluorosulfonic acid (PFSA)

Environmental Issues and ConcernsThe environmental impacts of electrolysis depend on the fuels and technologies used to generate the electricity used in the process.Use of conventional grid power would generate more global warming pollution than steam methane reforming with natural gas.Use of renewable power would allow for a truly low- or zero-emissions fuel cycle, but near-term benefits of renewable power may be greater if used to displace other sources of electricity rather than to create hydrogen.

Material Balance ProblemA plant produces H2 gas via steam reforming (assume CH4) . In the steam reforming step, 1500kg of methane was to be entered per hour.In the reformer: if steam was to be entered in excess (3:1 molar ratio), how much steam should be entered per hour?How much H2 gas can be produced per hour? (reformer + shift converter)How much CO2 is produced per hour? Assume complete conversion of CO to CO2.If only 80% of the CO produced from refining was converted into CO2 via water gas shift reaction, how much methane can be reproduced per hour?

OXYGEN AND NITROGEN

PROPERTIESOXYGEN- formula: O2 - weight: 32.00 g/mol- boiling point: -297.3oF- melting point: -361.9oFNITROGEN- formula: N2 - weight: 28.02 g/mol- boiling point: -320.5oF- melting point: -345.9oF

USESOXYGEN- production of steel in open-hearth or basic oxygen furnaces- used for removal of scale from billets by oxyacetylene flame and in oxygen lances for cutting out imperfections-used for disposal and conversion of refuse to usable by-products-used for aerating wastewater streams in the activated sludge process

USESOther uses of oxygen- metalworking applications- underground gasification- fireflooding- enhancement of combustion process in nonferrous mettalurgical processes- medical purposes in hospitals and aviators breathing oxygen-facilitates the forming and refining of glass

USESNITROGEN- used as a gaseous blanket that excludes oxygen and moisture- used for food freezing and as a refrigerant in the processing and refrigerated transport of frozen foods- used for tertiary oil recovery in oil fields- used to maintain pressure in the wells

Other uses of liquid nitrogen- low temperature metal treatment- shrink-fitting of parts- deflashing of molded plastic and rubber parts- cryobiology for storage of biological materials such as whole blood and bull semen- refrigerant in cryosurgical procedures

USES

MANUFACTURE OF O2 AND N2 Oxygen and Nitrogen are produced principally by the liquefaction and rectification of airSince air is composed of mainly O2 and N2 with some rare gases, air separation is commonly used for the production of not only oxygen, but also nitrogen and other rare gases.

TYPES OF AIR SEPARATIONCryogenic ProcessPressure Swing AdsorptionMembrane Process

CRYOGENIC SEPARATIONPioneered by Dr. Carl von Lindeprocess is used for medium to large scale plants which uses refrigeration by the heat exchangers to let the passing air be cooled for about 100K, letting the heavier oxygen settle at the bottom of the distillation column and the nitrogen evaporate to the top.

Argon and other rare gases are collected in between the column. A nitrogen-only plant is cheaper to operate compared to oxygen-only plant because of the ratio of nitrogen and oxygen in the air.

Pressure Swing Adsorption (PSA)Nitrogen PSAActivated carbon molecular sieve removes oxygen and other gases from the stream. The nitrogen produced is about 95 to 99.5% purity with pressures from 6 to 8 atm.

Oxygen PSAAlumina (Al2O3) is used to adsorb water vapor and zeolite molecular sieve is used to remove nitrogen and other gases to produce oxygen. Oxygen purity is about 90 to 95% with presence of argon of 4.5 to 5% of the content,

MEMBRANE PROCESSPressurized air passes through a molecular membrane, separating different gases. Nitrogen produced is at much lower purity with about 90 to 95%. It is much cheaper to produce nitrogen from membrane process compared to cryogenic process but some industries require high purity of nitrogen thus, membrane process is not used.

Pros and Cons of Different Air Separation

INDUSTRIAL GASRare Gases - Ar, Ne, Kr, XeBrief History on rare gasesYear Discoverer Discovery 1894Lord Rayleigh and Sir William Ramsay.Argon 1898Sir William Ramsay and Morris TraversNeon 1898Sir William RamsayKrypton1898Sir William RamsayNeon97Argon (Ar)Argon is the third noble gas, in period 8, and it makes up about 1% of the Earth's atmosphere.Argon has approximately the same solubility asoxygenand it is 2.5 times as soluble in water asnitrogen. This chemically inert element is colorless and odorless in both its liquid and gaseous forms. It is not found in any compounds.

98Neon (Ne)Neon is the second-lightest noble gas, its colour is reddish-orange in a vacuum discharge tube and in neon lamps.A colourless, odourless gas. Neon will not react with any other substance.

99Krpyton (Kr)Krypton is a rare atmospheric gas which is odorless, colorless, tasteless, nontoxic, monatomic and chemically inert. Krypton is present in the air at about 1 ppm. It is characterised by its brilliant green and orange spectral lines.

100Xenon (Xe)Xenon gas is odorless, colorless, tasteless, nontoxic, monatomic and chemically inert. The concentration of Xenon gas in the atmosphere, by volume percent, is 8.7 x 10-6.

101Rare gases Application and UsesArgon Application and UsesArgon is used to kill pigs humanely if there is an outbreak of some disease on the farm.

103Argon is used as a shielding gas in many welding applications.Shielding gas used in welding aluminium alloys or special steels;

Argon Application and Usesfill gas in lamps; lighting gas for gas discharge lamps;

105Argon Application and Usesgaseous extinguishing agent

106Argon Application and UsesArgon gas is used in graphite electric burners to prevent the graphite from burning. The graphite would burn in normal air with oxygen present.oxidation protection in the food industry;

107Krypton (Kr), Xenon (Xe) and Neon (Ne) Application and UsesKrypton (Kr), xenon (Xe) and neon (Ne) are mainly used as fill gases and operating gases in lamps and lasers.

The xenon headlights used in automotive construction are one well-known example. Not only are they significantly brighter than halogen headlights, but they also last longer. The gas which gives them their name, xenon, is required for a discharge process which produces the bright light. But halogen lamps are filled with noble gas mixtures, too. Xenon and neon are also the main components in the fill gas of plasma display screens. 108Modern xenon headlights turn night into day.

Xenon, mixed with other rare gases is used in eximer lasers for surgery (for example in eye surgery).

Xenon, mixed with other rare gases is used in eximer lasers for surgery (for example in eye surgery).Mixed with oxygen, it is used for CAT (Computer Aided Topography) scanning for mapping blood flow.Xenon is also being used as an anaesthetic.

110Feedstock and Process TechnologiesFeedstockBesides nitrogen and oxygen, the Earth atmosphere contains about 0.93 % of argon, 0.0018 % of neon, 0.000524 % of helium, 0.000114 % of krypton, and 0.0000086 % of xenon

The quantity of inert gases in one cubic meter of air is visually demonstrated in Figure.112For gas mixture separation by condensation methodsProcess Technologies113Manufacture of rare gasesArgonis obtained during the cryogenic manufacture of nitrogen and oxygen, using a separate distillation column mounted alongside the second (low pressure) column used to purify oxygen.At this point in the distillation process, the feed is typically 89% oxygen and 11% argon with only traces of nitrogen and is re-distilled to obtain argon of approximately 98% purity, known as Industrial Argon. When very high grade (99.999%) argon, Pure Liquid Argon (PLAR), is needed, industrial grade argon is processed in a separate plant, the Argon Purification Unit. This plant removes residual oxygen by mixing the gas stream with hydrogen and passing the mixture over a catalyst. Oxygen combines with hydrogen and the water formed is removed by passage through a molecular sieve. Residual nitrogen is then removed by further distillation at cryogenic temperatures.

Manufacture of rare gasesNeon(boiling point 27 K) does not condense out at the temperatures used in air separation plants and is withdrawn, with helium, and cooled to liquid nitrogen temperature. The helium is removed by adsorption on activated charcoal.Krypton and xenon(boiling points 120 and 165 K respectively) accumulate in the liquid oxygen and are obtained by further distillation.

ACETYLENE

PROPERTIESChemical formula: C2H2 Molecular weight: 26.04g/molBoiling point: -119.6oFMelting point: -113.4oF

USESIt has one of the hottest flame temperature of any commercially available fuel gas (5,720F), making it an excellent choice for welding, brazing and cutting steel alloys less than two inches thick.used as an instrumentation gas and a fuel gas and is the most important of all starting materials for organic synthesis

USESChloroprene and its polymer neoprene is the only chemical made mostly of acetyleneEmployed with oxygen in the manufacture of industrial chemicals such as vinyl chloride, acrylonitrile, acetic acid, trichloroethylene, and polyvinylpyrrolidone.

MANUFACTURE OF C2H2 manufactured by the action of water on calcium carbide: CaC2 + 2H2O C2H2 + Ca(OH)2 Two principal methods for generating C2H2 from CaC2 : - Batch carbide-to-water or wet method takes place in a cylindrical water shell surmounted by a housing with hopper and feed facilities

MANUFACTURE OF C2H2 A sealed hopper is kept filled with crushed calcium carbide and a slow moving worm carries the solid forward to fall into a three metre high reaction vessel (Figure 1).

The reaction occurs spontaneously on mixing and the gas formed passes via a hydraulic main to a gas holder where it is stored above water.

MANUFACTURE OF C2H2 iii. The addition of water to the reaction vessel is regulated manually. If the gas production becomes too rapid the reaction is slowed by the addition of more water, which lowers the temperature and hence the rate.

iv. The acetylene flows from the gas holder through a series of trays containing mainly ferric chloride to remove impurities such as hydrogen sulfide, phosphine and ammonia.

MANUFACTURE OF C2H2 v. The gas then passes through a drier containing calcium chloride. It is then compressed to 20 atmospheres and passed through another bed of calcium chloride to remove the last traces of water.

vi. The compressed gas is then pumped into cylinders or tankers where it dissolves in acetone to ensure it can be transported and handled safely.

MANUFACTURE OF C2H2 The major byproduct from the process is slaked lime Ca(OH)2 . This is dewatered in a series of settling ponds then sent to a waste disposal company. Some of the lime is dumped but the majority is used for lowering the pH of effluent water.

He, SO2, CO and N2OBecause all his friends argonHeliumFormulaHeMolecular Weight (lb/mol)4.00Critical Temperature (oF)-450.3Critical Pressure (psia)33.0Boiling Point (oF)-452.1Melting Point (oF)n/aSpecific Gravity0.138

UsesUsed with the mixture of Oxygen to provide a synthetic atmosphere for deep sea divers and tunnel workersHelium is employed to purge and pressurized spacecrafts

Production

Production

Sulfur DioxideFormulaSO2Molecular Weight (lb/mol)64.06Critical Temperature (oF)315.5Critical Pressure (psia)1142.0Boiling Point (oF)14.3Melting Point (oF)-103.9Specific Gravity2.285

UsesPure grade with less than 50 ppm of moisture is supplied for refrigeration

Serves as a raw material for production of sulfuric acid

As a bleaching agent in textile and food industries

An effective antichlor

Disinfectants in for wooden kegs and barrels

Controls fermentation of wine

A liquid solvent in petroleum refiningProduction of SO2

Carbon MonoxideFormulaCOMolecular Weight (lb/mol)28.01Critical Temperature (oF)-220.4Critical Pressure (psia)485.6Boiling Point (oF)-312.7Melting Point (oF)-337.1Specific Gravity0.985

UsesRaw material in the production of methanol and other alcoholsUsed in making diisocyanate and ethyl acrylateA chief constituent in making synthetic gases

ManufacturingThrough incomplete combustionBouduoard reactionCO2 + C -> 2 CO(H=170 KJ/mol)Endothermic reaction of steam and carbonH2O + C -> H2 + CO(H=131 KJ/mol)Direct Oxidation of Carbon in a limited supply of oxygen2C(s) + O2 -> 2CO(g)

Production of CO

Nitrous OxideFormulaN2OMolecular Weight (lb/mol)44.01Critical Temperature (oF)97.6Critical Pressure (psia)1053.3Boiling Point (oF)-128.3Melting Point (oF)-131.6Specific Gravity1.555

UsesUsed as laughing gas and NOS (Nitrous)

Usually used as an anesthetic

Production of N20