CuO and CuO–ZnO catalysts supported on CeO2 and CeO2–LaO3 for low temperature water–gas shift reaction

This paper describes an investigation on CuO and CuO–ZnO catalysts supported on CeO2 and CeO2–La2O3 oxides, which were designed for the low temperature water–gas shift reaction (WGSR). Bulk catalysts were prepared by co-precipitation of metal nitrates and characterized by energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), surface area (by the BET method), X-ray photoelectron spectroscopy (XPS), and in situ X-ray absorption near edge structure (XANES). The catalysts' activities were tested in the forward WGSR, and the CuO/CeO2 catalyst presented the best catalytic performance. The reasons for this are twofold: (1) the presence of Zn inhibits the interaction between Cu and Ce ions, and (2) lanthanum oxide forms a solid solution with cerium oxide, which will cause a decrease in the surface area of the catalysts. Also the CuO/CeO2 catalyst presented the highest Cu content on the surface, which could influence its catalytic behavior. Additionally, the Cu0 and Cu1+ species could influence the catalytic activity via a reduction–oxidation mechanism, corroborating to the best catalytic performance of the Cu/Ce catalyst.