Enhancement of Cu–Zn Interaction via Improved Cu–Zn Contact: Promoting Zinc Migration for Active Site Formation

The complexity and limited understanding of the modulation processes and mechanisms of conventional Cu–Zn–Al catalysts have hindered their widespread implementation. Here, we prepared Cu–Zn/γ-Al2O3 catalysts via the deposition–precipitation method to investigate the relationship among Cu–Zn content, contact, and interaction. We found that excessive Cu–Zn content leads to the aggregation of Cu and Zn species, while insufficient Cu–Zn content prevents effective separation of Cu by Zn. Additionally, the reduction and reaction processes of Cu–Zn/γ-Al2O3 were visualized. During the reduction process, ZnO (0 0 2) migrated to the catalyst surface, forming the ZnO (0 0 2)@Cu active site, where CO2 readily generates methanol via HCOO*. Therefore, enhanced Cu–Zn contact facilitates Zn migration, leading to the formation of active sites for methanol synthesis. The content-optimized 0.06Cu0.03Zn/Al2O3 exhibits 65.77% CO2 conversion and 88.32% methanol selectivity and displays better thermal stability than commercial CZA catalysts. We believe that our findings provide significant guidance and practical value for the industrialization of Cu–Zn catalysts in methanol synthesis.