Effect of Cu and Zn on the performance of Cu-Mn-Zn/ZrO2 catalysts for CO2 hydrogenation to methanol

CO2 hydrogenation to methanol is an important technology for carbon utilization which not only provides a solution to the greenhouse gas mitigation but also produces value-added products. Copper-based catalyst has always been the research focus of the process. Cu1.5Mn1.5O4 spinel has become an interesting alternative because it contains more oxygen defects and highly dispersed copper species that promote the CO2 adsorption and conversion. In this paper, the effects of Cu and Zn on the performance of Cu-Mn-Zn/ZrO2 catalysts for hydrogenation of CO2 to methanol were studied. It was found that after Zn modification, the catalytic performance of the catalyst was greatly improved. Among all catalysts, Cu3MnZn0.5Zr0.5 has the best CO2 conversion (7.14%) and methanol selectivity (69.74%) at 260 °C and 5 MPa. XPS analysis showed that doped Zn replaced the position of Cu in Cu1.5Mn1.5O4 spinel, forming the ZnOx and then increasing the content of oxygen defects, which resulted in the higher methanol selectivity. The increased Cu content promoted the activation of H2 and the rate of *CO3 hydrogenation to *HCOO, which in turn increases the conversion of CO2.