High-Performance Cu/ZnO/Al₂O₃ Catalysts for CO₂ Hydrogenation to Methanol

Abstract

Cu/ZnO/Al2O3 catalysts are widely used in methanol synthesis due to their low cost and high catalytic activity. The structural and surface characteristics of Cu are crucial to the formation of the active sites for methanol production. In this study, a series of methods for the synthesis of Cu/ZnO/Al2O3 are employed to modulate the catalyst structure and catalytic efficiency for the hydrogenation of CO2 to methanol. A correlation of catalytic activity with the Cu0 surface area and Cu particle sizes has been established. The Cu/ZnO/Al2O3 catalyst derived from hydrotalcite-like precursor (CZA-LDH) exhibits the maximum Cu0 specific surface area, the smallest Cu particle size, and high dispersion of elements, yielding the largest methanol production rate, which is comparable to the commercial Cu catalyst. Stability testing shows that the CZA-LDH catalyst can retain ∼94% of the initial activity. The in situ Fourier transform infrared spectroscopy analysis indicates that HCOO*, CH3O* intermediates, and product CH3OH are generated on the catalyst surface, and the reaction follows the formate pathway.