Roles of Metal-Organic Framework Supports in Base-Free Oxidation of 5-Hydroxymethylfurfural to Furan-2,5-Dicarboxylic Acid over Pt-Based Catalysts

The catalytic oxidation of 5-hydroxymethylfurfural (HMF) is an important process for producing a renewable furan-2,5-dicarboxylic acid (FDCA). Although several Pt-based catalysts have been reported to efficiently catalyze the oxidation of HMF, the functional roles of catalyst supports, as corroborated by spectroscopic techniques, have not been fully described. Here, we report on Pt nanoparticles supported on metal-organic frameworks (MOFs) that catalyze the oxidation of HMF to FDCA in the absence of base. Several catalysts are prepared by immobilizing pre-synthesized Pt nanoparticles on supports, allowing for the investigation of the role of the supports without the influence of the size of Pt nanoparticles (Pt NPs). By analyzing the catalytic performances along with the electronic properties using X-ray photoelectron spectroscopy and surface properties of the catalysts using in situ infrared spectroscopy of adsorbed CO₂, we find that the presence of Pt NPs in the metallic phase and basic hydroxyl groups on the support promote the HMF oxidation.