Base-free oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid over palygorskite-supported bimetallic Pt–Pd catalyst

Aerobic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2, 5-furandicarboxylic acid (FDCA) is an important reaction for producing green and sustainable chemicals. Herein, natural clay mineral palygorskite (Pal)-supported bimetallic Pt–Pd catalyst for the oxidation of HMF to FDCA in water without the addition of any bases was developed. The 1Pt9Pd1/Pal catalyst with Pt/Pd molar ratio of 9/1 exhibited excellent catalytic performance, and 100% HMF conversion and 99% FDCA yield were obtained under optimum reaction conditions after 12 h, which was mainly attributed to the synergy between palygorskite and bimetallic Pt–Pd nanoparticles. Palygorskite used as support realized the immobilization and dispersion of bimetallic nanoparticles, increasing the catalytic activity. The basicity of palygorskite and alloying effects between Pt and Pd facilitated the formation of FDCA by synergistically catalyzing the oxidation of alcohol and aldehyde groups in the reactants and intermediates. Furthermore, this catalyst showed good stability and reusability. The present work provides a highly efficient, cost-effective, and environmentally benign catalyst for the base-free oxidation of HMF to FDCA in practical industrial applications. •Efficient palygorskite-supported bimetallic Pt–Pd catalyst is synthesized.•The catalyst exhibits high activity for the base-free oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid.•The basicity of palygorskite and the alloying effect facilitate the formation of 2, 5-furandicarboxylic acid.