Solvent- and Base-Free Oxidation of 5-Hydroxymethylfurfural over a PdO/AlPO₄-5 Catalyst under Mild Conditions

A solvent-free method was proposed to upgrade the biomass-derived compound 5-hydroxymethylfurfural (HMF). The oxidation of HMF produce 2,5-furandicarboxylic acid (FDCA) has been examined in presence O2 without addition solvent and base. Different from conversion aldehyde group on as initial step H2O solvent, hydroxyl first oxidized FDCA finally generated solvent. role is replenish consumption active oxygen species catalyst surface. proceeded due effect. 83.6% selectivity at 38.8% measured with a PdO/AlPO4-5 80 °C for 5 h reaction mechanism proposed.