Insights into the structure-activity relationships of highly efficient CuCe oxides for the low temperature CO oxidation and CO-SCR

Abstract

A series of Cu-doped Ce-based mixed metal oxide catalysts were prepared by the simplest impregnation method for CO oxidation and CO selective reduction of NOx (CO-SCR), respectively. Among them, 10Cu/CeO2 catalyst showed excellent catalytic activity and stability in both reactions. The catalysts were characterized by XRD, BET, SEM, TEM, XPS, H2-TPR, Raman, O2-TPD and in-situ DRIFTS. The results show that the preferential exposure of the (111) crystal plane of CeO2 is beneficial to the dispersion of Cu species. The introduced Cu enters the surface or lattice of CeO2, exposeing more catalyst active sites, which improves the catalyst reducibility and activity. In addition, the introduction of Cu into Ce-based catalyst also increases the types of active oxygen on the catalyst surface, improves the mobility of oxygen, and thus enhances the activity of the catalyst. The in-situ DRIFTS analysis shows that CO oxidation follows the M − K mechanism with Cu+ as the core species, while CO-SCR follows the E-R mechanism at low temperature (50–150 °C) and the L-H mechanism at high temperature (200–400 °C). These results show that CuCeO2 bifunctional catalyst can simultaneously meet the requirements of CO oxidation and CO-SCR reaction, which is of great significance for environmental governance.