Engineering active sites at hydrotalcite-derived Cu-ZnO interaction for promoting CO2 hydrogenation to methanol

Abstract

The catalytic hydrogenation of CO2 to methanol presents a promising route for sustainable carbon utilization and neutrality, yet commercial Cu/ZnO/Al2O3 catalysts prepared by co-precipitation suffer from uneven metal dispersion and weak interface effect that decays methanol production efficiency. Herein, a series of layered composite oxide catalysts (LDO) are constructed via structural topotactic transformation of hydrotalcite precursors featuring precisely tuned Cu/Zn/Al ratios. Compared to CZA catalysts, the optimized LDO-1.4 catalyst achieves significantly enhanced CO2 conversion, methanol selectivity, and long-term stability. At 240 °C, it achieved a CO2 conversion rate of 20.8% with a methanol selectivity of 45.8%, exhibiting only a slight decline in activity during an 80-hour online test. A strong interaction between Cu and ZnO, as confirmed by multiple characterizations, results in highly dispersed Cu0 species and abundant oxygen vacancies, which is beneficial to enhance adsorption and activation of CO2 and H2. This interaction not only promotes the electron transfer at Cu-ZnO interfaces but also effectively reduces the hydrogenation energy barrier of the key intermediates, thereby obtaining excellent catalytic performance. Our study shows that using the hydrotalcite-derived method can efficaciously improve intrinsic weak interfacial interaction, paving the way for the rational design and application of Cu catalysts to CO2 hydrogenation.