Low-temperature CO oxidation on CuO/CeO2 catalysts: the significant effect of copper precursor and calcination temperature

Abstract

CuO/CeO₂ catalysts for CO oxidation were prepared by impregnation using different Cu precursors (acetate, nitrate, chloride, and sulfate) and calcined at 500 or 800 °C. Their physicochemical properties were characterized by TG-DSC, XRD, TEM, N₂ adsorption, Raman, XPS, H₂-TPR, CO-TPD, and DRIFTS. The results show that CuO is the dominant Cu species in all cases except for copper sulfate calcined at 500 °C, under which temperature some Cu₂(OH)₃Cl are also obtained from copper chloride. CuO/CeO₂ prepared from copper acetate and calcined at 500 °C shows the best activity for CO oxidation, due to the presence of more finely dispersed CuO and stronger synergistic effects. The synergistic effects can induce the formation of Cu⁺ (the better CO adsorption sites) and activate the lattice oxygen, thus exerting a crucial role in the catalytic process. However, the residual Cl⁻ and SO₄²⁻ have a negative effect on the synergistic effects, resulting in low activity in CO oxidation.