The water gas shift (WGS) and reverse water gas shift (RWGS) reactions are important in a great number of chemical processes where the adjustment of the relative amounts of CO2, CO and H2 is important. So-called "low temperature shift", LTS, catalysts, normally operating in the temperature range 175 to 325oC, have been commonly based on CuO/ZnO although Al2O3 is normally also present in commercial catalysts. Such LTS catalysts have also been almost universally used in the past two or three decades to promote the methanol-steam reforming reaction for the production of hydrogen. The general application for such hydrogen has been as the feed to a fuel cell.Our group has done extensive work in developing understanding of this methanol-steam reforming (MSR) process with one of the major objectives being development of the ability to predict CO production rates for a variety of process conditions. It is now generally agreed that the WGS/RWGS reactions play a significant role in determining the composition of the product gas leaving the reformer. Since most of our interest has been in PEM fuel cells, for which CO is a serious anode poison, much of our MSR work has been directed to the development of mechanistic reaction models which can be used to design processes with minimum CO yield. Two publications (Peppley et al, 1999a and 1999b) summarize our proposed MSR reaction model, a key feature of which is a proposed mechanistic WGS/RWGS model.The paper demonstrates the application of this WGS/RWGS model to kinetic data for feeds such as CO+H2O, CO2+ H2, and simulated reformate, H2/CO2/CO/H2O, mixtures. Test pressures were at or near atmospheric. Results are presented for two commercial catalysts- one a CuO/ZnO and the other a CuO/ZnO/Al2O3 formulation. The thermodynamic consistency of the kinetic results is discussed.
Surface structure–activity relationships of Cu/ZnGaO catalysts in low temperature water–gas shift (WGS) reaction for production of hydrogen fuel