Synthesis of dimethyl carbonate from CO2 and methanol over CeO2: Role of copper as dopant and the use of methyl trichloroacetate as dehydrating agent

The effect of copper as dopant on ceria (CeO2) was investigated in the direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol. Ceria with different copper loadings (0.02 and 0.5 wt%) was synthesized using the dry impregnation method and characterized by H-2-TPR, XRD, EPR, UV-VIS/DRS, acid-base properties and N-2 physisorption. CeO2 with 0.02 wt% of Cu showed the highest catalytic activity and selectivity to DMC, mostly due to its basic sites, associated with the presence of oxygen vacancies. Higher Cu concentration (0.5 wt%) promotes dehydrogenation, favoring the formation of methyl formate as the main product. Pure CeO2 also produced dimethoxymethane as by-product. To circumvent the thermodynamic limitations of the reaction, methyl trichloroacetate was tested as dehydrating agent, showing superior performance than 2-cyanopyridine, due to its higher reactivity toward hydrolysis. (C) 2019 Elsevier Inc. All rights reserved.