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

CO 2 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. Cu 1.5 Mn 1.5 O 4 spinel has become an interesting alternative because it contains more oxygen defects and highly dispersed copper species that promote the CO 2 adsorption and conversion. In this paper, the effects of Cu and Zn on the performance of Cu-Mn-Zn/ZrO 2 catalysts for hydrogenation of CO 2 to methanol were studied. It was found that after Zn modification, the catalytic performance of the catalyst was greatly improved. Among all catalysts, Cu 3 MnZn 0.5 Zr 0.5 has the best CO 2 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 Cu 1.5 Mn 1.5 O 4 spinel, forming the ZnO x and then increasing the content of oxygen defects, which resulted in the higher methanol selectivity. The increased Cu content promoted the activation of H 2 and the rate of *CO 3 hydrogenation to *HCOO, which in turn increases the conversion of CO 2. • Mn3+ induces partial reduction of ZnO for Cu-Mn-Zn/ZrO 2 catalysts. • Partial reduction of ZnO leads to the formation of oxygen defects. • Cu 3 MnZn 0.5 Zr 0.5 catalysts are efficient for CO 2 conversion to methanol • The intermediate *HCOO species are formed from the reaction of *CO 3 species either with *H or *H OH species • The production of methanol is controlled by the reaction of *HCOO with activated *H species. [ABSTRACT FROM AUTHOR]