Promoting effect of MnOx on the performance of CuO/CeO2 catalysts for preferential oxidation of CO in H2-rich gases

Abstract

A series of CuO/CeO2–MnOx catalysts with the Mn/(Ce + Mn) atomic ratios of 0, 0.2, 0.4, 0.6 and 1.0 were prepared and characterized by means of N2 adsorption, XRD, H2-TPR and XPS. The promoting effect of MnOx on the performance of CuO/CeO2 catalyst for the CO preferential oxidation in H2-rich gases (CO PROX) was investigated. The results show that the addition of MnOx can improve the catalytic activity of CuO/CeO2 catalyst. CuO/CeO2–MnOx catalysts exhibit much higher activity in the preferential oxidation of CO than CuO/CeO2 and CuO/MnOx. The CuO/CeO2–MnOx catalyst with the Mn/Ce + Mn atomic ratio of 0.4 is the most active, over which 100 % conversion of CO with selectivity of 83 % is obtained at 140 °C. The presence of MnOx in CuO/CeO2–MnOx catalysts can promote the release of oxygen species from ceria to active copper species and increase the highly dispersed copper species. XPS characterization further revealed that the surface hydroxyls/carbonates of catalysts decrease with the amount of Mn, which should be greatly responsible for the higher activity of CuO/CeO2–MnOx catalysts.