Understanding the formation of active site in copper ceria system for carbon dioxide catalytic conversion

Copper-based catalysts, particularly those supported by ceria (CeO 2 ), provide a cost-effective substitute for noble metals in hydrogenation reactions. The interaction between Cu and CeO 2 improves dispersion and generates essential active sites, such as Cu + and oxygen vacancies, vital for catalytic efficiency. This study explores the creation of active sites in Cu/CeO 2 catalysts through adjustments in metal content and calcination conditions. The findings reveal that the 2 wt.%Cu/CeO 2 catalyst calcined at 600 o C achieved the highest CO 2 conversion via reverse water gas shift reaction (RWGS) to CO, approximately 60% at 600 o C, with minimal coke formation. Additionally, the catalyst also exhibited reactivity in the dry reforming of methane at elevated temperatures (above 800 o C). The characterization data suggest that the strong interaction among finely dispersed CuO and the CeO 2 support enhances electron transfer, leading to a higher density of surface oxygen vacancies and Cu + species, which in turn promotes the redox cycle. The density of Cu + /(Cu + +Cu 2+ ) and surface oxygen vacancy correlates very well with the synthesis conditions and catalytic activity towards CO 2 conversion. The results suggest that Cu loading and calcination temperature in Cu/CeO 2 system could significantly enhance the presence of active sites for effective CO 2 hydrogenation. • Cu/CeO 2 catalysts surface oxygen vacancies are affected by Cu loading. • Catalyst calcination temperature also affects the surface oxygen vacancies. • Surface oxygen vacancies correlates linearly with Cu+ sites active on the surface. • A high density of oxygen vacancy results in greater conversion of CO 2 to CO.