Kinetic and activity study of CO oxidation over CuO-MnOx-CeO2 catalysts

Three CuO-MnOx-CeO2 catalysts with different impregnation sequences (i.e. MnOx/CuO/CeO2, CuO/MnOx/CeO2 and CuO-MnOx/CeO2) were prepared and the effects of impregnation sequences on the structures and catalytic behaviors of these catalysts were investigated. It was found that the MnOx/CuO/CeO2 possessed the largest amount of oxygen vacancies but the lowest reducibility; the CuO/MnOx/CeO2 had the largest Cu+ contents but the lowest amount of oxygen vacancies; the CuO-MnOx/CeO2 catalyst had the highest CuO dispersion and the best reducibility, along with moderate amount of oxygen vacancies and Cu+ contents on the surface. The kinetic studies revealed that the apparent activation energies of CO oxidation over the CuO-MnOx/CeO2, MnOx/CuO/CeO2 and CuO/MnOx/CeO2 were 49.5, 51.8 and 73.8 kJ mol(-1), in order, and the activities followed an order of CuO-MnOx/CeO2 > MnOx/CuO/CeO2 > CuO/MnOx/CeO2. The highest performance of the CuO-MnOx/CeO2 was ascribed to the highly dispersed CuO species and the mobility of lattice oxygen.