(625e) Efficient Cu-Based Catalysts for CO2 Hydrogenation to Methanol: An Exsolution Strategy with CuAl2O4 As Precursor

Catalytic conversion of carbon dioxide to methanol using green hydrogen produced from renewable energy is a potential process to achieve carbon reduction. Cu-based catalysts are of great interest due to their availability and high efficiency in hydrogenation reactions. For the rational design of Cu-based catalysts to further improve the reaction activity and space-time yield of methanol, it has been revealed that highly dispersed Cu particles, abundant oxygen vacancies, and reasonable surface Cu⁺ content are crucial for activating reactants and stabilizing reaction intermediates. This study focuses on the development of a selective exsolution method using CuAl₂O₄ spinel as precursor to regulate the dispersion and electronic structure of Cu species to obtain efficient Cu-based catalysts for CO₂ hydrogenation to methanol. After a suitable reduction treatment, the CuAl₂O₄ catalyst shows enhanced CO₂ conversion, better methanol selectivity, and 5.7 times higher methanol yield compared to the supported Cu/Al₂O₃ catalyst under the conditions of 240 °C and 3 MPa. The in-situ characterization of the exsolution process of CuAl₂O₄ demonstrates that highly dispersed Cu particles with an average particle size of 10 nm are formed. In contrast to the Cu/Al₂O₃ catalysts, abundant Cu⁺ species and oxygen vacancies are formed on the surface of CuAl₂O₄ due to the stronger metal-support interaction. It is expected to further improve the catalytic performance of Cu-based catalysts for CO₂ hydrogenation to methanol by adding various metal oxides (i.e., ZnO or ZrO₂) on the CuAl₂O₄ precursor and applying this exsolution strategy to construct copper-oxide interfacial sites while increasing the content of Cu⁺ species on the catalyst surface.