Heterogeneous Cu Catalyst for CO2-to-Methanol Hydrogenation Importance of Catalyst Precursor Structure

Cu-based catalyst is one of the major catalysts for CO2-to-methanol hydrogenation, but the catalytic perfor-mance must be further improved. This review introduces a new development strategy for Cu-based catalysts: Cu coordination structure in a catalyst precursor will control the morphology of the active sites. The strategy requires preparation of Cu-doped metal oxides containing unique Cu dusters. Cu doping allows (i) control of the crystal phase of the metal oxide support, (ii) formation of Cu nanoparticles with quite small size via H2 reduc-tion, and (iii) regeneration of the spent catalysts. Based on the strategy, we developed Cu/a-ZrO2 (a-= amor-phous) and Cu/MgAl2O4 for CO2-to-methanol hydrogenation. Crystal phase control and Cu nanoparticle forma-tion were related to the catalyst activity, whereas the regeneration ability was related to the catalyst durability. Control of the coordination structure of the active metal species in the catalyst precursor will lead to the develop-ment of improved catalysts and to the elucidation of the unique structure and behavior of the active metal species.