Improvement of surface properties of metal doped-CeO<inf>2</inf> nanospindle catalysts for direct synthesis of dimethyl carbonate from CO<inf>2</inf> and methanol

Abstract

To utilize carbon dioxide (CO2) which is the main greenhouse gas, this study developed effective metal doped-CeO2 nanospindle catalysts for conversion of CO2 and methanol into dimethyl carbonate (DMC). Ce0.9M0.1O2 nanospindles (where M is a transition metal, i.e., Zr, Fe, Cu and Co) were prepared by a template-free hydrothermal method. The substitution of different valence and size cations, including Zr4+, Fe3+, Cu2+ and Co2+, for Ce4+ sites in the fluorite CeO2 lattice induced the defect formation of surface-active sites of exposed Ce3+ and oxygen vacancies through the charge compensation and redox pair reactions. Ce0.9Fe0.1O2 solid solution with well-preserved spindle shaped morphology showed the highest catalytic performance by giving DMC yield at 3.56 mmol.gcat−1 with 100% DMC selectivity. The improvement of catalytic activity was attributed to the higher proportion of surface defect sites and variation of acid-base properties caused by the integration of Fe dopants into CeO2 ionic system.