Synergistic effects of Pr doping on oxygen vacancies and metal dispersion in Ru/CeO2 catalysts for enhanced ethylene methoxycarbonylation activity

The reaction rate of alkoxycarbonylation is typically lower when using heterogeneous catalysts compared to homogeneous catalysis, primarily due to the reduced ability of the active sites to activate the reactants. To address the insufficient activation of reactants on the Ru/CeO 2 catalyst for ethylene methoxycarbonylation, this study investigates the doping of CeO 2 with Pr 3+ ions. By substituting Ce 4+ with Pr 3+ in the CeO 2 , richer oxygen vacancies are generated, which enhance the activation of CH 3 OH. This doping significantly increases the reaction rate of ethylene methoxycarbonylation to methyl propionate (MP), achieving a rate of 86.1 g·g Ru -1 ·h −1 while maintaining a selectivity of over 99 %. Notably, Pr doping also induces the formation of Ru-O-Ce species in the catalyst, which hinders the reduction of Ru species. However, this hindered reduction is counterbalanced by the enhanced dispersion of Ru species, as Pr doping promotes the formation of smaller Ru nanoparticles. Thus, an optimal level of Pr doping exerts a synergistic effect by positively influencing both the CeO 2 support and the Ru metal, thereby improving their respective abilities to activate the reactants and enhancing the overall performance in the ethylene methoxycarbonylation reaction to produce MP.