Cpi - Industrial Gases (chap.7)

Chemical Process Industry

INDUSTRIAL GASES

What 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 in industry and are also gaseous at ambient temperature and pressure. They are chemicals which can be an elemental gas or a chemical compound that is either organic or inorganic, and tend to be low molecular weight molecules. They could also be a mixture of individual gases. They have value as a chemical; whether as a feedstock, 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 gases”  is 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 high purity or 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 is processed for later use of its energy rather than manufactured for use as a chemical substance or preparation. • The oil and gas industry 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 for hydrocarbons produced by the petroleum industry directly from natural resources or in an oil refinery.

What defines an industrial gas? • The petrochemical industry is also seen as distinct. So petrochemicals (chemicals derived from petroleum) such as ethylene are 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? • Manufactured fuel gas (such as town gas) would historically have been considered an industrial gas. Syngas is often considered to be a petrochemical; although its production is a core industrial gases technology. Similarly, projects harnessing Landfill gas or biogas, Waste-to-energy schemes, 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?

Who needs the industrial gases?

CARBON DIOXIDE

PROPERTIES

• • • • •

Chemical formula: CO2 Molecular weight: 44.01 g/mol Boiling point: -78.5 oC Melting point: -55.6 oC Density: 1.977

PROPERTIES

• Colourless • Odorless • Soluble in water, ethanol, and acetone

PROPERTIES

• • • • •

Linear covalent molecule Acidic oxide CO2 + H2O ==> H2CO3 CO2 + NaOH ==> NaHCO3 NaHCO3 + NaOH ==> Na2CO3 + H2O

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

USES • • • • • • • • •

use in carbonation of beverages treatment of drinking water wastewater neutralization greenhouse fertilizer coolant cleaning agent (as dry ice); Transport refrigerant for food refrigeration firefighting paper recycling

USES • Carbon 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 - recovery - recovery - recovery - recovery

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

MANUFACTURE OF CO2 CO2 from the combustion of fuel oil in a boiler 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. 23kg 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 GAS HYDROGEN PRODUCTION

Brief History on Hydrogen •

1520

-The first discovery of hydrogen gas by Swiss Alchemist Philippus Aureolus Paracelsus

•

1766

-Hydrogen was first identified as a distinct element by British scientist Henry Cavendish

•

1788

-French Chemist Antoine Lavoisier gave hydrogen its name. “hydro” and “genes”, meaning “water” and “born of”

•

1800

-English scientists William Nicholson and Sir Anthony Carlisle discovered electrolysis

•

1920

-The first commercial technology – the electrolysis of water to produce pure hydrogen

•

1959

-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 tractor

•

1960

-The industrial production of hydrogen shifted slowly towards a fossil-based feedstock

•

1990

-The world’s first solar powered hydrogen production plant at Solar-WasserstoffBayern, a research and testing facility in southern Germany

Hydrogen (H2) odorless, • Colorless,

tasteless, flammable and nontoxic gas at atmospheric temperatures and pressures • The most abundant element in the universe • Not an energy source, but is an energy vector or carrier

Hydrogen Application and Uses

Hydrogen Application and Uses

Metals Chemicals,

Pharmaceuticals and Petroleum Glass and Ceramics Food and Beverages Electronics Miscellaneous

Feedstock and Process Technologies

Feedstock • Fossil Resources - Natural Gas - Coal • Renewable Resources - Biomass - Water with input from renewable energy sources

• Renewable Energy Sources - Sunlight - Wind - Wave or Hydro-Power

Process Technologies • Reforming of Natural Gas • Gasification of Coal and • -

Biomass Splitting of Water by: Water-electrolysis Photo-electrolysis (Photolysis) Photo-biological Production (biophotolysis) High Temperature Decomposition

Thermochemical Sulfur-Iodine Process

High-Temperature Decomposition • High-temperature splitting of water occurs at about 3000 C. 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 cycles Hybrid systems coupling thermal decomposition and electrolytic decomposition Direct catalytic decomposition of water with separation via a ceramic membrane (thermo-physic cycle) Plasma-chemical decomposition of water in a doublestage CO2 cycle 0

• -

Thermo-chemical Water Splitting Cycles

• The conversion of water into hydrogen and oxygen by a series •

of thermally driven chemical reactions They were extensively studied in the late 1970s and 1980s, but have been of little interest in the past 10 years

*An example of a thermochemical process is the Sulfur-Iodine Cycle

Sulfur-Iodine Cycle Reactions

• H2SO4→ SO2 + H2O + ½

O2 • I2 + SO2 + 2H2O → H2SO4 + 2HI • 2HI → I2 + H2 Overall Balance • H2O → H2 + ½ O2

Section 1 – Bunsen Reaction and Chemical recycle

Section 2 – Sulfuric Acid Concentration and Decomposition

Section 3 – Hydrogen Iodide Decomposition

Thermo-chemical Water Splitting (SodiumIodide Cycle) Advantages

Disadvantages

• Net plant efficiencies up to

• High Efficiency is attained at

•

•

• • •

~50% Products are only Oxygen and Hydrogen Endothermic All reagents used are recycled; no effluents Needs least development among all other thermochemical cycles

high temperature, ≥ 8000C * Still a developing technology

Peak Process Temperature (deg. C)

Environmental Issues and Concerns

3 Different Approaches to Alleviating the Problems Associated with the Energy Hunger of Humanity 1.Preventing the cause of global warming to escape into the atmosphere (i.e. CO2 sequestration), known as the “clean fossil hydrogen” option 2.A drastic efficiency increase in energy usage 3.A transition from fossil fuels to sustainable, carbon dioxide neutral ones

STEAM REFORMATION

STEAM REFORMATION

• Steam reforming or Fossil fuel reforming is a process used to produce hydrogen from hydrocarbon fuels such as natural gas and coals.

Steam Reformation: Flow Diagram

Hydrogen Production via Steam Reformation • Feedstock Purification • Steam Reformation • Gas Conversion • •

-High Temperature Shift Conversion -Low Temperature Shift Conversion Purification Pollution Control Technologies

Feedstock Purification • Removal of poisons such as sulphur and •

chloride to maximize the life of the downstream steam reforming and other catalysts The best way to remove sulphur compounds is to convert the organic sulphur species to H2S over a hydrodesulphurization catalyst C2H5SH + H2 → C2H6 + H2S

• •  The next step is sulphur removal with an absorbent

Feedstock Purification • Catalyst -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 species

Steam Reforming

CH4 + H2O → CO + 3 H2

CxHy + H2O «=» x CO + (x + 0.5y) H2 • 700–1100 °C • Highly endothermic • The reaction takes place across a nickel catalyst packed in tubes in a fired furnace • An excess of steam is used to promote the reforming reaction and avoid carbon deposition on the catalyst. 

Shift Conversion CO + H2O  CO2 + H2 • ΔH°reac = −41.16 kJ⋅mol−1 at 298.15 K

• High Temperature Shift Conversion •

(water-gas shift reaction) Low Temperature Shift Conversion

High Temperature Shift Conversion • Increases the hydrogen yield • • •

by driving the water-gas shift reaction to the right About 350ºC (662ºF) inlet temperature Lowers the CO level from 1015 mol % (dry) to 1-2 mol % (dry) Catalyst:  Fe3O4 (magnetite)

Low Temperature Shift Conversion • Enables increased hydrogen yield by further moving the • • •

water-gas shift equilibrium in favour of H2 190-210ºC (374-410ºF) inlet temperature Lowers the CO level from 1-2 mol % (dry) to 0.1-0.2 mol % (dry) Catalyst: Raney copper catalyst

Product Purification • Pressure Swing Absorption Unit • Four basic process steps:

•

– Adsorption – Depressurization – Regeneration – Repressurization 99.99% product hydrogen

Environmental Issues and Concerns

• this method of producing hydrogen contributes to global

warming unless associated carbon emissions are captured and stored

Methanation

• removes 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 ELECTROLYSIS • • • •

Electrolysis is a method of using a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis of water is the decomposition of water (H 2O) into oxygen (O2) and hydrogen gas (H2) due to an electric current being passed through the water. Electrolyzer Hydrogen produced via electrolysis can result in zero greenhouse gas emissions, depending on the source of the electricity used

Water Electrolysis: History • since the early 1900s • Nicholson and Carlisle were the first to discover the ability of • • •

electrolytical water decomposing By 1902 more than 400 industrial water electrolysis units were in operation and in 1939 the first large water electrolysis plant went into operation In 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.

• The 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=Faraday’s 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) electrolysis

• PEM electrolysers require no liquid electrolyte (solid), which • • •

simplifies the design significantly. No caustic electrolyte in circulation The heart of a PEM or SPE electrolyser is a proton exchange membrane (or solid polymer) electrolyte Disadvantage: limited lifetime of the membranes

PEM

• The amount of gases produced per unit time is directly • • •

related to the current that passes through the electrochemical cell In pure water at the negatively charged cathode, a reduction reaction takes place, with electrons (e−) from the cathode being given to hydrogen cations to form hydrogen gas At the positively charged anode, an oxidation reaction occurs, generating oxygen gas and giving electrons to the anode to complete the circuit The minimum necessary cell voltage is Ecell = 1.21 V

• Anode structure: porous • •

titanium and activated by a mixed noble metal oxide catalyst Cathode structure: porous graphite current collector with either Pt or a mixed oxide as electrocatalyst Membrane: Perfluorosulfonic acid (PFSA)

Environmental Issues and Concerns

• The 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 zeroemissions 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 Problem A plant produces H2 gas via steam reforming (assume CH4) . In the steam reforming step, 1500kg of methane was to be entered per hour. a) In the reformer: if steam was to be entered in excess (3:1 molar ratio), how much steam should be entered per hour? b)How much H2 gas can be produced per hour? (reformer + shift converter) c) How much CO2 is produced per hour? Assume complete conversion of CO to CO2. d)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

PROPERTIES •OXYGEN -

formula: O2 weight: 32.00 g/mol boiling point: -297.3oF melting point: -361.9oF

•NITROGEN - formula: N2 - weight: 28.02 g/mol - boiling point: -320.5oF - melting point: -345.9oF

USES • OXYGEN - 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 byproducts -used for aerating wastewater streams in the activated sludge process

USES • Other 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

USES • NITROGEN - 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

USES • 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

MANUFACTURE OF O2 AND N2 • Oxygen and Nitrogen are produced principally by the liquefaction and rectification of air • Since 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 SEPARATION • Cryogenic Process • Pressure Swing Adsorption • Membrane Process

CRYOGENIC SEPARATION • Pioneered by Dr. Carl von Linde • process 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 PSA • Activated 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 PSA • Alumina (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 PROCESS • Pressurized 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 GAS  Rare Gases - Ar, Ne, Kr, Xe

Brief History on rare gases Year 1894

1898

1898 1898

Discoverer Lord Rayleigh and Sir William Ramsay. Sir William Ramsay and Morris Travers  Sir William Ramsay Sir William Ramsay

Discovery Argon

Neon

Krypton Neon

Argon (Ar) is the third noble •Argon

gas, in period 8, and it makes up about 1% of the Earth's atmosphere. •Argon has approximately the same solubility as  oxygen and it is 2.5 times as soluble in water as  nitrogen . •This chemically inert element is colorless and odorless in both its liquid

Neon (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.

Krpyton (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

Xenon (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.

Rare gases Application and Uses

Argon Application and Uses • Argon is used to kill pigs humanely if there is an outbreak of some disease on the farm.

• Shielding gas used in welding aluminium alloys or special steels;

Argon is used as a shielding gas in many welding applications.

Argon Application and Uses • fill gas in lamps; • lighting gas for gas discharge lamps;

Argon Application and Uses • gaseous extinguishing agent

Argon Application and Uses • Argon 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;

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

Modern xenon headlights turn night into day.

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

Feedstock and Process Technologies

Feedstock • Besides 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

Process Technologies

• For gas mixture separation by condensation methods

Manufacture of rare gases • Argon is 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 gases

• Neon (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

PROPERTIES

Chemical formula: C2H2 Molecular weight: 26.04g/mol Boiling point: -119.6oF Melting point: -113.4oF

USES  It has one of the hottest flame temperature of any commercially available fuel gas (5,720°F), 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

USES • Chloroprene and its polymer neoprene is the only chemical made mostly of acetylene • Employed 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 i. 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). ii. 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 N2O

Because all his friends argon

Helium • • • • • • •

Formula He Molecular Weight (lb/mol) 4.00 Critical Temperature (oF) -450.3 Critical Pressure (psia) 33.0 Boiling Point (oF) -452.1 Melting Point (oF) n/a Specific Gravity 0.138

Uses • Used with the mixture of Oxygen to provide a synthetic atmosphere for deep sea divers and tunnel workers • Helium is employed to purge and pressurized spacecrafts

Production

Production

Sulfur Dioxide • • • • • • •

Formula

SO2

Molecular Weight (lb/mol) 64.06 Critical Temperature (oF) 315.5 Critical Pressure (psia) 1142.0 Boiling Point (oF) 14.3 Melting Point (oF) -103.9 Specific Gravity 2.285

Uses • Pure 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 refining

Production of SO2

Carbon Monoxide • • • • • • •

Formula CO Molecular Weight (lb/mol) 28.01 Critical Temperature (oF) -220.4 Critical Pressure (psia) 485.6 Boiling Point (oF) -312.7 Melting Point (oF) -337.1 Specific Gravity 0.985

Uses • Raw material in the production of methanol and other alcohols • Used in making diisocyanate and ethyl acrylate • A chief constituent in making synthetic gases

Manufacturing • • • • • • •

Through incomplete combustion Bouduoard reaction CO2 + C -> 2 CO (H=170 KJ/mol) Endothermic reaction of steam and carbon H2O + C -> H2 + CO (H=131 KJ/mol) Direct Oxidation of Carbon in a limited supply of oxygen 2C(s) + O2 -> 2CO(g)

Production of CO

Nitrous Oxide • • • • • • •

Formula

N2O

Molecular Weight (lb/mol) 44.01 Critical Temperature (oF) 97.6 Critical Pressure (psia) 1053.3 Boiling Point (oF) -128.3 Melting Point (oF) -131.6 Specific Gravity 1.555

Uses • Used as laughing gas and NOS (Nitrous)

• Usually used as an anesthetic

Production of N20