NO reduction by CO over CuO–CeO2 catalysts: effect of preparation methods

This work is mainly focused on investigating the influence of preparation methods on the physicochemical and catalytic properties of CuO–CeO2 catalysts for NO reduction by CO model reaction. Five different preparation methods have been used to synthesize CuO–CeO2 catalysts: mechanical mixing method (MMM), impregnation method (IM), grinding method (GM), hydrothermal treatment method (HTM) and co-precipitation method (CPM). All of these samples were characterized by a series of techniques such as N2-physisorption, XRD, LRS, H2-TPR, ICP-AES, XPS, in situ FT-IR and NO + CO model reaction. The obtained results show that the catalytic performances of these CuO–CeO2 catalysts can be ranked by CuCe-IM > CuCe-CPM > CuCe-GM > CuCe-HTM > CuCe-MMM, which is in agreement with the orders of the surface oxygen vacancy concentration, reducibility and Cu+ content, suggesting that the synergistic effect between Cu+ species and surface oxygen vacancies of these CuO–CeO2 catalysts plays an important role in this model reaction. In order to further understand the synergistic effect, a possible reaction model is tentatively proposed.