CuO and CuO–ZnO catalysts supported on CeO 2 and CeO 2–LaO 3 for low temperature water–gas shift reaction

Abstract

This paper describes an investigation on CuO and CuO–ZnO catalysts supported on CeO 2 and CeO 2–La 2O 3 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/CeO 2 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/CeO 2 catalyst presented the highest Cu content on the surface, which could influence its catalytic behavior. Additionally, the Cu 0 and Cu 1+ species could influence the catalytic activity via a reduction–oxidation mechanism, corroborating to the best catalytic performance of the Cu/Ce catalyst.