Flower-Shaped Zinc Oxide Nanostructures Loaded with Au Nanoparticles for Efficient and Highly Stable Production of Dihydroxyacetone from Glycerol Oxidation

The selective oxidation of glycerol to dihydroxyacetone (DHA) represents a critical method for efficiently utilizing glycerol, a primary byproduct of biodiesel production. However, the challenge of balancing catalyst activity and recycling stability significantly limits the practical application of this process. Herein, the glycerol conversion performance is effectively modulated by controlling the nanostructure of the support in Au-supported catalysts. Zinc oxide carriers with morphologies of nanorods (NRs), nanoflowers (NFs), and nanoparticles (NPs) are successfully prepared and loaded with Au nanoparticles (NPs) to obtain a series of Au/ZnO-Z catalysts. Among them, the catalyst composed of flower-shaped zinc oxide nanostructures loaded with Au NPs (Au/ZnO-NF) exhibits optimal performance, with a glycerol conversion of 92.9% and a DHA selectivity of 69.5%. Notably, Au/ZnO-NF demonstrates exceptional cycling stability surpassing most of the currently reported catalysts, maintaining a glycerol conversion of 75.2% and a DHA selectivity of 75.1% even after five cycles. Comprehensive characterization and experimental analysis demonstrat that the Au/ZnO-NF catalysts exhibit low reduction temperatures, the smallest Au nanoparticle size, excellent crystallinity, and significantly enhance adsorption of O₂ and the adsorption and conversion of polyols at glycerol secondary hydroxyl moiety.