CeO₂/Beta composite catalysts in dimethyl carbonate synthesis from CO₂: effect of preparation method on surface oxygen species

Two kinds of CeO₂/Beta composite catalysts were prepared by precipitation method (CeB-p) and hydrothermal method (CeB-h), respectively. The physicochemical properties of all samples were studied in detail by combining XRD, XPS, SEM, TEM, N₂ sorption, NH₃-TPD and CO₂-TPD techniques. CeB-p catalyst exhibited a higher dimethyl carbonate (DMC) yield than the CeB-h catalyst at the similar conditions for DMC synthesis from CO₂ and methanol. This enhanced activity of CeB-p catalyst was attributed to enhanced acid–base properties modulated by abundant surface lattice oxygen species rather than oxygen vacancies. Compared with the inertly adsorbed methoxy induced by the oxygen vacancy enriched CeB-h, abundant surface lattices oxygen species in CeB-p catalyst facilitated the formation of weakly absorbed methoxy species, which resulted in the shift of the rate-determining step and the reduction of reaction energy barrier. This study offered guidance for the rational design and fabrication of high-performance DMC synthesis catalysts based on CeO₂/Beta composite.