Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid over MnO_x-CeO₂ Supported Palladium Nanocatalyst under Aqueous Conditions

Selective aerobic oxidation of biomass-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, particularly as an important renewable alternative to petroleum-derived terephthalic acid in the synthesis of useful polymers. Herein, a novel MnO_x−CeO₂ (MC) supported palladium catalyst was synthesized and applied for the aerobic oxidation of HMF into FDCA in KHCO₃ aqueous solution. The physical and chemical properties of the obtained catalysts were systematically characterized by TEM, N₂ adsorption and desorption, XRD, TG, XPS, and H₂-TPR characterization methods. And the highest yield of FDCA at 92.5 % was achieved under the optimal reaction conditions. Moreover, regeneration tests revealed the synthesized Pd/MC catalyst can be recovered and reused at least five times without significant loss of catalytic activity. The developed facile reaction system with Pd/MC catalysts offers a new route to large-scale and economically viable processes for the oxidation of HMF into FDCA.