Pr-doped CeO2-loaded Ru-based catalysts for ethylene methoxycarbonylation

The industrial production of methyl propionate synthesized via methoxycarbonyl esterification of ethylene achieved 100% atom economy. In this study, we synthesized ruthenium-loaded praseodymium–cerium oxide (Pr–CeO2) catalysts by precipitation impregnation and evaluated their performance in the methoxycarbonylation reaction of ethylene. The effect of Pr doping on the reaction results was analyzed by characterization and mechanistic studies. Pr doping increased the concentration of localized oxygen vacancies in the catalysts and thus modulated the catalytic effect of Lewis acid–base pairs. The increase of local oxygen vacancies significantly enhanced the activation and dissociation of CH3OH. At the same time, since the dissociation activation of the other two feedstock molecules, ethylene and CO, occurred at the Ru site, Pr doping facilitated the dispersion of Ru to a certain extent, thus increasing the dissociation activation of CO and ethylene, which, in combination with Pr doping, further increased the content of oxygen vacancies in the active site as methanol, resulting in a substantial enhancement of the dissociation activation of the feedstock molecules, which then increased the catalytic reaction rate through synergistic effects. The results provide a new perspective for the future study of methoxycarbonylation.