Zr-Doped CuZnGa Catalyst Increased Oxygen Vacancy to Promote CO₂ Adsorption for Thermochemical Methanol Synthesis

Thermochemical methanol synthesis from CO2 hydrogenation over Cu/ZnO-based catalysts generally suffers from low CO2 adsorption and poor methanol selectivity. To address this issue, a Zr-doped CuZnGa catalyst with abundant oxygen vacancies was prepared to promote CO2 adsorption. Incorporation of Zr promoted electron transfer from Zr atoms to Cu atoms and Zn atoms, which strengthened the metal–support interaction between Cu/ZnO through electronic rearrangement. XPS and EPR results showed that the 2%Zr-CuZnGa catalyst generated more oxygen vacancies on Cu/ZnO interfaces to increase weak and moderately basic sites. In situ DRIFT spectra indicated that these oxygen vacancies promoted the formation of HCO3*, which was further hydrogenated to form key active intermediates HCOO* and CH3O* in the formate pathway. Zr incorporation enhanced CO2 adsorption on the Cu/ZnO interface of the 2%Zr-CuZnGa catalyst, which achieved higher CO2 conversion (22.0%) and methanol STY (0.540 gMeOH g–1 h–1 compared to the CuZnGa catalyst under the conditions of GHSV = 12,000 h–1, CO2:H2 = 1:3, P = 5 MPa, and T = 250 °C.