Doping effect of CuO on CeO2 for CO oxidation

Cu-Ce-O catalysts, prepared by the amorphous citrate precursor (ACP) method, were investigated by ICP, XRD and micro-reactor techniques. At low copper content of Cu-Ce-O catalysts, fluorite structures formed at low calcining temperatures, and CuO doped into the CeO2 matrix; at high copper content, in addition to the fluorite structure, crystalline monoclinic phase CuO formed as well at high calcining temperatures. There was no other phase formed even calcined at 1000 degrees C. The results show that only a little CuO dopes into the CeO2 matrix to form complex oxide, which promotes the catalytic activity of CO oxidation greatly. The optimum Cu-Ce-O catalyst is composed of 15% copper by Cu/(Ce+Cu) atomic ratio, and calcined at 700 degrees C for 4h. The phase compositions include the crystalline CuO and the active complex oxide with fluorite structure. The formulation of the active complex oxide is Cu0.06Ce0.94O1.94.