Facet-dependent Pd0-O2−-Ce3+ active site for selective hydrogenation of linoleate ester to cis oleic acid ester

Abstract

Reducing the formation of trans fatty acid in vegetable oil hydrogenation process is of significance to ensure food safety. Herein, Pd0-O2−-Ce3+ active site was constructed by strong electronic interactions between Pd0 and CeO2-Polyhedrons to promote the formation of cis fatty acid. Results reveal that the abundant oxygen vacancies of CeO2 (111) facets promote the adsorption and activation of hydrogen, leading to excellent catalytic activity of Pd/CeO2-Polyhedrons. Moreover, electronic reconstructed Pd0-O2−-Ce3+ active site limits the σ-bond rotation of half-hydrogenated intermediates through enhancing π backdonation and weakening the σ-bond, contributing to the reduction of trans products. Under mild conditions (30 °C, 0.3 MPa H2, and 2 h), Pd/CeO2-Polyhedrons catalyst shows exceptional methyl oleate selectivity of 52.6% with 93.8% conversion for sunflower oil hydrogenation. The catalyst has been further extended to the selective hydrogenation to several other vegetable oils such as sunflower oil, peanut oil, soybean oil, among others, under mild conditions.