  Water gas shift (WGS) reaction is a chemical reaction in which carbon
monoxide reacts with water vapor to form carbon dioxide and hydrogen. It is an
important reaction industrially used in conjunction with steam reforming of
hydrocarbons for the production of high purity hydrogen. Grenoble et al
examined the roles of both active metals and metal oxide support on the
kinetics of the WGS reaction. They found out that the turn over numbers of
various Al2O3 supported transition metals decreased in the trend of Cu, Re, Co,
Ru, Ni, Pt, Os, Au, Fe, Pd, Rh, and Ir, which corresponds nicely to the
observed volcano shaped correlation between catalytic activities and respective
CO adsorption heat. This is a strong indication that CO gets activated on the
metal surface during the reaction and different metals have different
activation energies. The authors also observed that the turn over number of
Pt/Al2O3 was one order of magnitude higher than that of Pt/SiO2, indicating a
strong support effect, which the authors ascribed to the activation of H2O.
