Characteristics and combustion/decomposition activities of CuO/mordenite

Abstract

Various amounts of copper oxide were loaded by impregnation of copper salt solution on dealuminated mordenites and redox-treated at 500°C and 750°C. The catalysts were characterized by XRD, ESR, H₂-TPR and O₂-TPD, and tested for the combustion of methane, acetone, benzene and 1-hexene, and NO decomposition. The redox-treatment induced most of the copper to exist as a CuO crystallite on the mordenite and its reducibility decreased as the temperature increased. Redox-treatment at 750°C reduced the crystallinity of the mordenite and increased the size of the CuO crystallite, especially for the samples with a higher CuO content. The optimum amount of copper for the combustion was 3–5 wt.%. However, the activity of the NO decomposition increased with the amount of CuO present. Maximum activities were observed for both the combustion and the NO decomposition when the ratio of silica/alumina was 20∼30. These results suggest that forming CuO crystallites, including clusters and ion exchanged Cu²⁺ ions, on dealuminated mordenite by the impregnation of copper salt is desirable for the preparation of the catalysts for combustion/NO decomposition.