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Water gas shift reaction

 

 
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The water-gas shift reaction (WGS/Dussan Reaction) is a chemical reaction
Chemical reaction

A chemical reaction is a process that always results in the interconversion of chemical substances. The substance or substances initially involved in a chemical reaction are called reactants....
 in which carbon monoxide
Carbon monoxide

Carbon monoxide, with the chemical formula CO, is a colorless and odorless, tasteless, yet highly toxic gas. Its molecules consist of one carbon atom covalent bond to one oxygen atom....
 reacts with water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
 to form carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 and hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
:
CO + H2O ? CO2 + H2


The water-gas shift reaction is an important industrial reaction. It is often used in conjunction with steam reforming
Steam reforming

Steam reforming , hydrogen reforming or catalytic oxidation, is a method of producing hydrogen from hydrocarbons. On an industrial scale, it is the dominant method for producing hydrogen....
 of methane or other hydrocarbon
Hydrocarbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. With relation to chemical terminology, aromatic hydrocarbons or arenes, alkanes, alkenes and alkyne-based compounds composed entirely of carbon or hydrogen are referred to as "pure" hydrocarbons, whereas other hydrocarbons with bonded com...
s, which is important for the production of high purity hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
 for use in ammonia
Ammonia

Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....
 synthesis.






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Encyclopedia


The water-gas shift reaction (WGS/Dussan Reaction) is a chemical reaction
Chemical reaction

A chemical reaction is a process that always results in the interconversion of chemical substances. The substance or substances initially involved in a chemical reaction are called reactants....
 in which carbon monoxide
Carbon monoxide

Carbon monoxide, with the chemical formula CO, is a colorless and odorless, tasteless, yet highly toxic gas. Its molecules consist of one carbon atom covalent bond to one oxygen atom....
 reacts with water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
 to form carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 and hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
:
CO + H2O ? CO2 + H2


The water-gas shift reaction is an important industrial reaction. It is often used in conjunction with steam reforming
Steam reforming

Steam reforming , hydrogen reforming or catalytic oxidation, is a method of producing hydrogen from hydrocarbons. On an industrial scale, it is the dominant method for producing hydrogen....
 of methane or other hydrocarbon
Hydrocarbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. With relation to chemical terminology, aromatic hydrocarbons or arenes, alkanes, alkenes and alkyne-based compounds composed entirely of carbon or hydrogen are referred to as "pure" hydrocarbons, whereas other hydrocarbons with bonded com...
s, which is important for the production of high purity hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
 for use in ammonia
Ammonia

Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....
 synthesis. The water-gas shift reaction was discovered by Italian physicist Felice Fontana
Felice Fontana

Felice Fontana , was an Italy physicist who discovered the water gas shift reaction in 1780. He is also credited with launching modern toxicology and investigating the human eye....
 in 1780. The reaction is slightly exothermic
Exothermic

File:Explosion1.JPG In thermodynamics, the term exothermic describes a process or reaction that releases energy usually in the form of heat, but also in form of light , electricity , or sound....
, yielding 42 kJ (10 kcal) per mole.

The carbon monoxide can also be generated by bogs or other waste regenerative means by physical/chemical processes such as bog and landfill fires.

Applications

This reaction has been used as a CO removal method from the reformate for fuel cell applications.

The reverse water gas shift reaction has recently found a possible application in In-Situ Resource Utilization
In-Situ Resource Utilization

In space exploration, In-Situ Resource Utilization describes the proposed use of resources found or manufactured on other planetary bodies or planetoids to further the goals of a space mission....
 on Mars to provide oxygen for fuel for the Mars Direct
Mars Direct

Mars Direct is a proposal for a relatively low-cost manned mission to Mars with current rocket technology. The plan was originally detailed in a research paper by Robert Zubrin and David Baker in 1990....
 mission concept.

Reaction Conditions

The water gas shift reaction is sensitive to temperature, with the tendency to shift towards reactants as temperature increases due to Le Chatelier's principle
Le Châtelier's principle

In chemistry, Le Chatelier's Principle, also called the Le Chatelier-Braun principle, can be used to predict the effect of a change in conditions on a chemical equilibrium....
. In fuel-rich hydrocarbon combustion processes, the water gas reaction at equilibrium state is often employed as a means to provide estimates for molar concentrations of burnt gas constituents.

The process is used in two stages, stage one a high temperature shift (HTS) at 350 °C (662 °F) and stage two a low temperature shift (LTS) at 190-210 °C (374-410 °F). Standard industrial catalysts for this process are iron oxide promoted with chromium oxide for the HTS step and copper on a mixed support composed of zinc oxide and aluminum oxide for the LTS shift step.

Catalysts

Attempts to lower the reaction temperature of this reaction have been done primarily with a catalyst such as Fe3O4 (magnetite
Magnetite

Magnetite is a ferrimagnetism mineral with chemical formula Iron3Oxygen4, one of several iron oxides and a member of the spinel group....
), or other transition metal
Transition metal

In chemistry, the term transition metal has two possible meanings:*It commonly refers to any element in the d-block of the periodic table, including the group 12 element elements zinc, cadmium and Mercury ....
s and transition metal oxides
Transition metal oxides

Transition metal oxides comprise a class of materials that contain transition metals and oxides. Well known materials include Yttrium barium copper oxide....
. Another catalyst is the Raney copper catalyst.

See also

  • Water gas
    Water gas

    Water gas is a Syngas, containing carbon monoxide and hydrogen. It is an useful product but requires careful handling because of the risk of carbon monoxide poisoning....
  • In-Situ Resource Utilization
    In-Situ Resource Utilization

    In space exploration, In-Situ Resource Utilization describes the proposed use of resources found or manufactured on other planetary bodies or planetoids to further the goals of a space mission....
  • PROX
    PROX

    PROX is an acronym for PReferential OXidation, and refers to the preferential oxidation of a gas on a catalyst.The catalyser preferentially oxidises carbon monoxide using a heterogeneous catalyst placed upon a ceramic support....