Role of Metal Oxides in Cu-Based Catalysts with NaBH4 Reduction for the Synthesis of Methanol from CO2/H2

Abstract

Cu/ZnO catalyst was prepared with NaBH4 reduction instead of high temperature H2 reduction to relieve the aggregation of Cu species. With the purpose of strengthening the interaction between Cu species and ZnO, some Al2O3, Y2O3, ZrO2 promoters are introduced to promote the synthesis of methanol from CO2/H2. The introduction of metal oxide promoters improves the dispersion of Cu species, decreases the onset reduction temperature and increases the quantity of basic sites. The Cu/ZnO/ZrO2 catalyst exhibited the highest CH3OH yield of 0.20 g mL−1 h−1 with CO2 conversion of 22.8% and CH3OH selectivity of 56.2% at 543 K. The catalytic activity is closely correlated to the exposed Cu surface area and a synergistic effect between the Cu species and metal oxides was proposed, which promoted the catalytic conversion of CO2 as well as H2 and simultaneously facilitated the migration of atomic hydrogen from Cu sites to metal oxides through spillover.