Characterization and Activity of Cu‐MnOx/γ‐Al2O3 Catalyst for Hydrogenation of Carbon Dioxide

Abstract The effect of manganese on the dispersion, reduction behavior and active states of surface of supported copper oxide catalysts have been investigated by XRD, temperature‐programmed reduction and XPS. The activity of methanol synthesis from CO2/H2 was also investigated. The catalytic activity over CuO‐MnOx/γ‐Al2O3 catalyst for CO2 hydrogenation is higher than that of CuO/γ‐Al2O3. The adding of manganese is beneficial in enhancing the dispersion of the supported copper oxide and make the TPR peak of the CuO‐MnKx/γ‐Al2O3 catalyst different from the individual supported copper and manganese oxide catalysts, which indicates that there exists strong interaction between the copper and manganese oxide. For the CuO/γ‐Al2O3 catalyst there are two reducible copper oxide species; α and β peaks are attributed to the reduction of highly dispersed copper oxide species and bulk CuO species, respectively. For the CuO‐MnOx/γ‐Al2O3 catalyst, four reduction peaks are observed, α peak is attributed to the dispersed copper oxide species; β peak is ascribed to the bulk CuO; γ peak is attributed to the reduction of high dispersed CuO interacting with manganese; δ peak may be the reduction of the manganese oxide interacting with copper oxide. XPS results show that Cu+ mostly existed on the working surface of the Cu‐Mn/γ‐Al2O3 catalysts. The activity was promoted by Cu with positive charge which was formed by means of long path exchange function between CuOMn. These results indicate that there is synergistic interaction between the copper and manganese oxide, which is responsible for the high activity of CO2 hydrogenation.