Cooperative effect between copper species and oxygen vacancy in Ce_(0.7−x)Zr_(x)Cu_(0.3)O_(2)catalysts for carbon monoxide oxidation

摘要

The effects of Zr doping on the existence of Cu and the catalytic performance of Ce_(0.7−x)Zr_(x)Cu_(0.3)O_(2)for CO oxidation were investigated.The characterization results showed that all samples have a cubic structure,and a small amount of Zr doping facilitates Cu^(2+)ions entering the CeO2 lattice,but excessive Zr doping leads to the formation of surface CuO crystals again.Thus,the number of oxygen vacancies caused by the Cu^(2+)entering the lattice(e.g.,Cu^(2+)-□-Ce^(4+);□:oxygen vacancy),and the amount of reducible copper species caused by CuO crystals,varies with the Zr doping.Catalytic CO oxidation tests indicated that the oxygen vacancy and the reducible copper species were the adsorption and activation sites of O_(2)and CO,respectively,and the cooperative effects between them accounted for the high CO oxidation activity.Thus,the samples x=0.1 and 0.3,which possessed the most oxygen vacancy or reducible copper species,showed the best activity for CO oxidation,with full CO conversion obtained at 110°C.The catalyst is also stable and has good resistance to water during the reaction.