Influence of the preparation method on the performance of CuO-CeO2 catalysts for the selective oxidation of CO

In this work we report on the influence of the preparation method on the physicochemical and catalytic properties of CuO-CeO2 catalysts for the selective CO oxidation in simulated reformate gas. Four CuO-CeO2 samples were prepared using the co-precipitation, the citrate-hydrothermal, the urea-nitrates combustion, and the impregnation methods, and characterized by N-2 adsorption-desorption, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction by H-2 (TPR-H-2). The combustion-prepared sample exhibited the best catalytic performance, closely followed by that prepared with the citrate-hydrothermal method. The co-precipitated sample was less active followed by the impregnated one. The activity of all samples decreases in the presence of CO2 and, to a higher degree, in the simultaneous presence of both CO2 and H2O in the feed. The resistance to this deactivation was higher in the case of the sample prepared by the urea-nitrates combustion method, which remained the most active and selective, closely followed by the specimen prepared by the citrate-hydrothermal method. The superior catalytic performance of the samples prepared by the urea-nitrates combustion and the citrate-hydrothermal methods is attributed to the existence of well dispersed, strongly interacting with the ceria surface, copper oxide species. (C) 2004 Elsevier B.V. All rights reserved.