CeO₂-Decorated α-Fe₂O₃ Nanorings for the Direct Synthesis of Dimethyl Carbonate from CO₂ and Methanol

Abstract

α-Fe2O3 nanorings (NRs) were decorated with CeO2 and used as a catalyst for the direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol. The α-Fe2O3 NR was prepared by microwave-assisted hydrothermal synthesis followed by the precipitation of cerium nitrate at different Ce/Fe atomic ratios (1:1, 1:2, and 1:5) and then calcined at 400 °C. The characterization of the catalysts suggested the interaction between the oxides upon modification of the α-Fe2O3 NR with the CeO2 nanoparticles, forming mixed oxide interfaces. The synergy between CeO2 and α-Fe2O3 shows a maximum for the CeFe11 (1:1 atomic ratio) catalyst, which also presented the highest concentration of oxygen vacancies and specific surface area. This mixed oxide exhibited the highest catalytic activity for the direct synthesis of DMC, which may be interpreted in terms of the presence of oxygen vacancies and the (110) exposed plane on the CeO2 surface. Furthermore, the reuse of the catalyst showed good stability after three cycles. The CeFe11 can also be used together with trichloromethyl acetate (MTCA) as a dehydrating agent to shift the equilibrium and increase the yield of DMC, indicating the potential of the system for the direct synthesis of DMC from CO2 and methanol.