Direct synthesis of dimethyl carbonate from methanol and carbon dioxide over Co-Ce-Zr ternary metal solid solution

Abstract

To investigate highly performance catalysts for the direct synthesis of dimethyl carbonate (DMC) from carbon dioxide (CO₂) and methanol, a Co_0.02/Ce_0.7Zr_0.3O₂ ternary metal solid solution nanoparticle catalyst was synthesized, demonstrating superior performance with a DMC yield of 3.86 mmol g⁻¹ and selectivity of 100 % at 7 MPa and 140 °C. A series of characterizations further validated the successful incorporation of cobalt and zirconium into the crystal lattice of CeO₂, resulting in an increased number of acid-base sites on its surface and a rise in oxygen vacancy content from 10.1 % to 28.7 %. The density functional theory (DFT) calculation results further corroborated the experimental findings, indicating that the doping of cobalt and zirconium ions significantly reduced the formation energy of oxygen vacancies on the catalyst surface from 2.53 to −1.38 eV, while concurrently decreasing the adsorption energy of CO₂ from −0.33 to −1.74 eV. Additionally, charge calculation results revealed that oxygen vacancies functioned as Lewis acid sites, whereas lattice oxygen atoms served as Lewis base sites, facilitating the cooperative activation of CO₂. The results may provide a new approach for designing and improving CeO₂-based catalysts for CO₂ activation.