Highly Efficient and Stable Bimetallic AuPd over La-Doped Ca-Mg-Al Layered Double Hydroxide for Base-Free Aerobic Oxidation of 5-Hydroxymethylfurfural in Water

As a promising renewable alternative to the production of petroleum-derived chemicals and energy, biomass transformation is attracting increasing attention in terms of green chemical processes and sustainable development. Specifically, selective aerobic oxidation of cellulose-derived 5-hydroxymethylfurfural (HMF) into high value-added 2,5-furandicarboxylic acid (FDCA) is regarded as one of the most attractive biomass transformations due to a wide range of its application prospects. Herein, we report the synthesis of a highly efficient and stable bimetallic AuPd nanocatalyst over the La-doped Ca-Mg-Al layered double hydroxide (La-CaMgAl-LDH) support for base-free aerobic oxidation of HMF to FDCA in water, which makes the biomass-based chemical process green and cost effective. Under optimized reaction conditions, the yield of FDCA can reach above 99%. Such encouraging performance of the catalyst is believed to be correlated with both the higher surface basicity of La-CaMgAl-LDH support and the synergy between Au-Pd atoms in the bimetallic AuPd nanoparticles, which can greatly favor the activation of reactants and reaction intermediates in the course of tandem oxidation reactions. The present work provides an effective strategy for developing highly efficient bimetallic catalysts with the enhanced stability by adjusting surface structures and compositions of supports for a wide range of base-free aerobic oxidation of other biomass-derived compounds in water.