From the article:
The water-gas shift reaction is important as a method for further enhancing the yield of hydrogen from industrial processes such as the steam reforming of natural gas or the gasification of heavy carbonaceous materials. Syngas mixtures containing mostly hydrogen and carbon monoxide are typically generated at elevated temperatures via the combustion of natural gas, coal, bio-mass, petroleum and organic wastes (Wender, 1996). Steam is then added to the CO – H2 feed mixture prior to being introduced to water-gas shift, WGS, reactors to convert the CO to CO2 and additional H2.
However, thermodynamic equilibrium favors high conversion of CO and steam to hydrogen and carbon dioxide at low temperatures. Therefore, the water-gas shift reaction is commonly conducted at low temperature in the presence of catalysts that enhance the reaction rate.
The water-gas shift reaction is reversible, and several correlations for the equilibrium constant have been published (Moe, 1962; Benson, 1981; Babieri and DiMaio, 1997; Singh and Saraf, 1977). A simple temperature-dependent correlation (Moe, 1962) was used in this study.