Generating Strong Metal-Support Interaction and Oxygen Vacancies in Cu/MgAlO_x Catalysts by CO₂ Treatment for Enhanced CO₂ Hydrogenation to Methanol

Strong metal-support interactions (SMSIs) are essential for optimizing the performance of supported metal catalysts by tuning the metal-oxide interface structures. This study explores the hydrogenation of CO2 to methanol over Cu-supported catalysts, focusing on the synergistic effects of strong metal-support interaction (SMSI) and oxygen vacancies introduced by the CO2 treatment to the catalysts on the catalytic performance. Cu nanoparticles were immobilized on Mg-Al layered double oxide (LDO) supports and modified with nitrate ions to promote oxygen vacancy generation. Further calcination in a 15% CO2/85% N2 atmosphere at various temperatures not only resulted in the formation of SMSI and electronic metal-support interaction (EMSI) between Cu and MgO, but also generated abundant oxygen vacancies on MgO. The optimized 7.5%Cu/MA-C700 catalyst (Cu supported on MgAl-LDO treated in CO2 at 700 °C) exhibited significantly higher methanol production and turnover frequency compared to the air-calcined counterparts. In situ FTIR studies further revealed that oxygen vacancies led to the formation of more monodentate formate species, thus enhancing methanol production. This research provides a novel approach to engineering the catalyst interface structure and the interaction between the active metal and the support, particularly for the irreducible metal oxide support, for efficient hydrogenation of CO2 to methanol.