| Pd-based catalysts are effective for CO2 hydrogenation to methanol. In this study, a series of x% Pd/ZnO (x=1, 3, 5) catalysts were prepared using a precipitation-impregnation method, along with PdM/ZnO (M = In, Zn, Bi) catalysts with different metal dopants. The catalytic performance was evaluated, and the morphology, structure, and chemical states of the catalysts before and after the reaction were characterized. TEM characterization results revealed that Pd was loaded onto the surface of nano-ZnO in the form of PdO particles with an average size of approximately 3.5 nm. After the reaction, the Pd species on the catalyst surface were transformed from PdO into metallic Pd0 and PdZn alloy phases. Catalytic performance evaluation showed that lower reaction temperatures (e.g., 250 °C) were more favorable for methanol production, with the 1% Pd/ZnO catalyst exhibiting the best performance among the tested samples. The introduction of secondary metal dopants such as In, Zn, and Bi contributed to a more uniform dispersion of Pd particles and effectively suppressed side reactions. Among these, Bi doping led to the highest CO2 conversion and methanol selectivity. |
