Investigation of synthesis parameters to fabricate CeO2 with a large surface and high oxygen vacancies for dramatically enhanced performance of direct DMC synthesis from CO2 and methanol

• Published in: Molecular catalysis 2022-08, Vol.528, p.112471, Article 112471
• Main Authors: Yang, Guanling, Jia, Aizhong, Li, Jingde, Li, Fang, Wang, Yanji
• Format: Article
• Language: English
• Subjects: Dimethyl carbonate; Direct synthesis; High surface area; Oxygen vacancy; Porous CeO2
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2022.112471

•A facile method to synthesize efficient CeO2 catalyst was developed.•The prepared CeO2s possess a large surface area and high oxygen vacancies.•A large number of Oxygen vacancies were fabricated by reorganization and/or oxygen etching.•Weak and moderate acid-base sites are catalytically active sites.•Strong acid sites are the key reason for the decrease in catalytic activity. Hierarchically porous CeO2 with excellent catalytic performance for direct dimethyl carbonate (DMC) from CO2 and methanol was successfully prepared by a simple hydrothermal method due to the abundant oxygen vacancies (Ovs, ∼17%) and large surface area (137 m2·g−1). The effects of template dosage as well as synthesis parameters including hydrothermal time and calcination temperature on the physicochemical properties of as-synthesized CeO2 were studied, and the reaction conditions were investigated and optimized. The obtained results indicated that the Ovs varied with prolonging hydrothermal time and more Ovs were formed by etching due to longer crystal time. And the fabricated Ovs acting as acid sites and basic sites effectively activated CO2 and methanol, respectively, which was further confirmed by the simulation results, however, the strong acid sites are detrimental to catalyst stability due to their strong chemical interactions with nicotinamide. And a high DMC yield of 260.12 mmol∙g−1 was obtained under the optimal reaction conditions: reaction time 5 h, initial CO2 pressure 4.0 MPa, and reaction temperature 140 °C. High oxygen vacancies were facilely fabricated for synthesized CeO2, which acts as efficient activity sites for adsorbing and activation of CO2, thus giving an excellent catalytic activity. And the synthetic parameters displayed an obvious effect on the physicochemical properties of prepared CeO2. [Display omitted]