Identification of the Active Sites on ZnO/ZrO2 for CO2 Hydrogenation to CO and Methanol

Interest in identifying the structure of the catalysts in the reaction atmosphere has grown, but it remains challenging, especially when the changes only occur on the surface. Herein, we track the reaction-induced structural changes of ZnO/ZrO2 and their consequent effects on the activity and selectivity of CO2 hydrogenation. Utilizing a combination of in situ infrared and controlled experiments, we meticulously investigate the dynamic changes of the catalyst's surface structure with time on stream. The reaction-driven growth of ZnOx clusters is correlated with the enhanced CO2 hydrogenation activity of ZnO/ZrO2. Furthermore, in situ infrared results show that the aggregation of ZnOx clusters promotes hydrogen activation, thereby facilitating the synthesis of methanol. The modification of the interfacial sites confirms the significance of the ZnO–ZrO2 interface as the main site for CO formation, while the surface of ZnOx clusters predominantly contributes to methanol synthesis at low zinc loading. These findings advance our comprehension of the structure–activity relationship of zinc-based catalysts for CO2 hydrogenation.