Direct Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide Catalyzed by Cerium-Based High-Entropy Oxides

Fluorite high entropy oxides (HEOs) were synthesized by anchoring method and Ce 0.5 (LaPrSmY) 0.5 O 2-y used as catalysts for synthesis of dimethyl carbonate (DMC) from methanol (CH 3 OH) and carbon dioxide (CO 2 ), the yield of DMC was up to 7.6 mmol/g at 140 ℃ and 8.0 MPa. Under the same reaction conditions, the time to reach reaction equilibrium was reduced by half compared HEOs with CeO 2 . The structure of HEOs were characterized by X-ray diffraction (XRD), specific surface area and pore size analyzer (BET), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The results showed that there are five metal elements of Ce, La, Pr, Sm and Y in the lattice of layered fluorite-type HEOs Ce x (LaPrSmY) 1-x O 2-y . The synergistic effect among the elements led to the lattice distortion and the generation of a large number of oxygen vacancies, which improved the reaction rate. Graphical Abstract The rare earth metal ions were anchored on the graphene oxide by electrostatic interaction and then calcinated to obtain fluorite high entropy oxides (HEOs) Ce x (LaPrSmY) 1-x O 2-y . Ce 0.5 (LaPrSmY) 0.5 O 2-y were used as catalysts for synthesis of dimethyl carbonate (DMC) from methanol (CH 3 OH) and carbon dioxide (CO 2 ), the yield of DMC was up to 7.6 mmol/g at 140 °C and 8.0 MPa. Under the same reaction conditions, the time to reach reaction equilibrium was reduced by half compared with CeO 2 attributed to the abundant oxygen vacancies on the surface and the excellent electron transfer ability.