Gold-Catalyzed Base-Free Oxidation of Glycerol to Dihydroxyacetone over Au/ZnO: Reaction Kinetics and Modeling

High Resolution Image Download MS PowerPoint Slide The selective catalytic oxidation of glycerol to dihydroxyacetone (DHA) has emerged as a promising route for glycerol valorization; however, kinetic studies under base-free conditions remain limited, especially for gold-based and commercial catalysts. In this work, glycerol oxidation kinetics were investigated using a commercial Au/ZnO catalyst in a semibatch reactor under base-free aqueous conditions (313–363 K, 2.5–6.5 bar O 2 ). Additional experiments using DHA as the reactant were performed to elucidate oxidation pathways. Mass transfer limitations were systematically evaluated and ruled out. The catalyst showed moderate DHA selectivity (47%), achieving a yield of 28% after 2 h. The reaction network was successfully described using a Langmuir–Hinshelwood–Hougen–Watson model, enabling the estimation of kinetic and adsorption parameters. The activation energy for glycerol oxidation (49 kJ mol –1 ) was consistent with literature values for noble-metal catalysts. Catalyst deactivation upon reuse was attributed to strong adsorption of reaction products, particularly glycolic acid.