Support size engineering boosts oxide-support interaction over In2O3/m-ZrO2 for CO2 hydrogenation to methanol

The hydrogenation of CO 2 to methanol is a promising strategy for renewable carbon utilization, where indium oxide loaded zirconia catalysts have been extensively studied. However, the influence of monoclinic zirconia (m-ZrO 2 ) support size on the structure-activity relationship remains insufficiently understood. Here, we systematically investigate the size effect of m-ZrO 2 supports on the structure, surface chemistry, and catalytic performance of In 2 O 3 /m-ZrO 2 catalysts. Comprehensive characterizations reveal that an optimal ZrO 2 grain size (∼13 nm) is associated with strengthened In 2 O 3 -ZrO 2 interaction and an increased concentration of thermally induced oxygen vacancies. In-situ DRIFTS confirms a formate-mediated pathway and enhanced formate intermediates conversion. Consequently, 5 %In/Zr-600 exhibits the highest methanol yield (0.43 g MeOH g cat −1 h −1 ). In comparison, smaller supports suppress methanol selectivity due to weak interfacial interaction, while larger supports promote In 2 O 3 crystallization and cause surface area loss, limiting activity and stability. These findings provide insight into how support grain size influences metal oxide and support interactions and catalytic behavior within the In 2 O 3 /m-ZrO 2 system.