Uncovering the role of yttrium in a cerium-based binary oxide in the catalytic conversion of carbon dioxide and methanol to dimethyl carbonate

Abstract

Cerium(IV) oxide (CeO2)-based materials are effective catalysts for the synthesis of dimethyl carbonate (DMC) from carbon dioxide (CO2) and methanol (CH3OH). Herein, 5% Y–CeO2 was synthesized by the co-precipitation method. It forms a solid solution structure, which leads to the highest concentration of oxygen vacancies. The Y–VO–Ce active site created by Y3+ doping enhances the adsorption and activation of CO2 based on moderately passivating CH3OH adsorption. Consequently, 5% Y–CeO2 exhibited the highest CH3OH conversion rate of 0.8% and a DMC yield of 15 mmol⋅(g cat)−1, which is 1.4 times of pure CeO2 (reacting in a stainless-steel autoclave at 140 °C with a stirring speed of 1000 r⋅min−1 and an initial pressure of 3.0 MPa for 2 h). An adsorption test and in situ diffuse reflectance infrared Fourier transform spectroscopy showed that 5% Y–CeO2 could effectively inhibit the formation of triple-bonded methoxy species, and promote the formation of bidentate carbonate and bridged methoxy intermediates, which is conducive to the improvement of reaction activity.