Liquid-Phase Oxidation of Ethylene Glycol on Pt and Pt–Fe Catalysts for the Production of Glycolic Acid: Remarkable Bimetallic Effect and Reaction Mechanism

Abstract

A highly active and selective Pt–Fe alloy catalyst on CeO2 support is reported in this work for aqueous phase oxidation of ethylene glycol (EG) to glycolic acid. The Pt–Fe nanoparticles are highly alloyed with a face-centered cubic (fcc) type of crystal structure and a chemical state of Pt0/Fe0, as confirmed from X-ray diffraction and extended X-ray absorption fine structure characterizations, respectively. Compared to the monometallic Pt catalyst, the Pt–Fe catalyst shows more than a 17-fold higher initial TOF, while achieving complete EG conversion in 4 h at 70 °C and ambient O2 pressure under alkaline conditions. The synergistic bimetallic effect occurs due to significantly changing the O2 adsorption-dissociation characteristics on the catalyst surface. The addition of a base shows a promotional effect on both Pt and Pt–Fe catalysts at low NaOH concentrations but an inhibition effect is observed for both catalysts at sufficiently high NaOH concentrations. Furthermore, the base enhances the synergistic effect observed with Pt–Fe catalyst.