Silica-modulated Cu-ZnO-Al2O3 catalyst for efficient hydrogenation of CO2 to methanol

Cu/ZnO/Al2O3 catalyst has been widely studied in the hydrogenation of CO2 to methanol, but it still suffers from insufficient catalyst stability and methanol selectivity. Herein, we overcome these issues by introducing the silica promoter to the catalyst, achieving the Cu/ZnO/Al2O3/SiO2 (CZAS) catalysts with significantly improved methanol selectivity and catalyst durability. Characterizations of samples showed that the silica species efficiently hindered the sintering of Cu nanoparticles during the catalysis, exhibiting constant performances in the continuous tests. In addition, the silica also electronically modulated the Cu nanoparticles that result in abundant Cuδ+ species in the catalyst, which minimized the methanol decomposition to improve the methanol selectivity, compared with the silica-free Cu/ZnO/Al2O3 catalyst. As a result, the CZAS exhibited CO2 conversion at 12.6 % and methanol selectivity at 85.1 %, giving a one-pass methanol yield at 10.7 %. The strategy in this work might provide an efficient route for enhancing the current industrial catalysts.