Highly efficient aerobic oxidation of 5-hydroxymethylfurfural to 2,5-fur- andicarboxylic acid over halloysite nanotubes-templated nitrogen-doped carbon supported bimetallic AuPd catalyst

Aerobic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2, 5-furandicarboxylic acid (FDCA) is an important way to produce bioplastic monomer. Herein, halloysite nanotubes (HNT)-templated layered porous hollow rod-shaped nitrogen-doped carbon supported bimetallic AuPd catalysts (AumPdn/HRNxC) with different nitrogen contents and bimetallic nanoparticles size were employed for the highly efficient aerobic oxidation of HMF to FDCA in sodium carbonate aqueous solution. Catalytic experimental results uncovered the possible re-action pathway, and the kinetics study further confirmed the oxidation of intermediate FFCA to FDCA was the rate-controlled step. Benefiting from the synergy between nitrogen-doped carbon support and bimetallic nano -particles, the Au3Pd1/HRN5C catalyst obtained the highest HMF conversion of 100% and FDCA yield of 99.9% under the optimal reaction conditions. In-situ FT-IR study revealed the adsorption configuration of HMF, and the ESR test proved that the active substance was superoxide radical. Furthermore, the catalyst showed good stability and reusability. This work provides an efficient, economical and environmentally friendly raw clay mineral derived heterogeneous catalyst for the large-scale production of FDCA from HMF.