Synthesis of glycolic acid by selective oxidation of ethylene glycol over Pt/Sn-Beta in a base-free medium

Abstract

Glycolic acid finds extensive applications in the production of biodegradable polymers, pharmaceuticals, and fine chemicals. In this study, a Pt catalyst supported on the Sn-Beta zeolite (Pt/Sn-Beta) was developed to achieve the efficient and highly selective catalytic oxidation of ethylene glycol with molecular oxygen to prepare glycolic acid at near-room temperature (30 °C). Characterization results, including XRD, TEM, XPS, FT-IR, and O₂-TPD, revealed that the relatively uniform dispersion of Pt particles, the optimal density of Lewis and Brønsted acid sites in the catalyst, and the synergistic interaction between Sn and Pt sites might be key factors contributing to the excellent catalytic performance of the Pt/Sn-Beta catalyst. By optimizing the reaction conditions, a 90% conversion of ethylene glycol and an 81% selectivity of glycolic acid were obtained. Furthermore, Pt/Sn-Beta exhibited excellent stability, with no significant decrease in catalytic performance after six repeated uses.