NO reduction by CO over CuO–CeO2catalysts: effect of preparation methods

Abstract

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.