On the issue of the active site and the role of ZnO in Cu/ZnO methanol synthesis catalysts

The problem concerning the active site and the role of ZnO in Cu/ZnO-based methanol synthesis catalysts can be consistently explained based on the literature results by distinguishing CO2 and CO hydrogenations. Although only metallic copper has some activities for methanol synthesis by the hydrogenation of CO2, Cu-Zn alloying in Cu particles is responsible for the major promotional role of ZnO in industrial Cu/ZnO-based catalysts. The morphology effect reported in the literature will probably appear for the system of highly dispersed Cu particles supported on ZnO. As for the hydrogenation of CO, Cu+ species or Cu-O-Zn sites are the active sites for methanol synthesis. The spillover effect of the Cu-ZnO system is not significant compared to the effect of ZnO on the creation of the Cu-O-Zn site.