Elucidation dynamics of ZnO and ZrO2 in catalytic CO2 Hydrogenation: An in-situ TEM study

Cu/ZnO/ZrO 2 (CZZ) catalysts are widely used in CO 2 hydrogenation to methanol. However, their structural dynamics under reaction conditions and related reaction mechanism remain unclear. In this study, we employed in-situ transmission electron microscopy (TEM) to investigate structural changes in Cu/ZnO/ZrO 2 catalysts under CO 2 and H 2 /CO 2 environments at 200°C and 250°C. Under CO 2 conditions, coexisting CuO and ZnO phases were observed along with a diminishing crystalline ZrO 2 phase. Under H 2 /CO 2 conditions, dynamic formation and evolution of a CuZn alloy phase occurred, accompanied by the reappearance of crystalline ZrO 2 nanoparticles. It is also noted that copper in Cu/ZnO/ZrO 2 is difficult to be completely reduced in a H 2 /CO 2 environment, in contrast to un-supported CuO nanoparticles. These results suggest a distinct function of ZrO 2 and ZnO support in the catalyst, which alters the catalytic performance of the CZZ system. The findings of this study provide new insight into the dynamic behavior of CZZ catalysts under actual reaction conditions.