Selective oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid over MnOx-CeO2 composite catalysts

The selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) has attracted much attention recently, as FDCA could be used as a polymer precursor to produce recyclable bio-based polymers. But most studies focused on the design of noble metal catalysts for the efficient oxidation of HMF to FDCA, here, non-noble metal catalysts, MnOx-CeO2 mixed oxides, were prepared by a co-precipitation method and used in the direct aerobic oxidation of HMF to FDCA. As high as 91% yield of FDCA was achieved over the MC-6 (Mn/Ce = 6) catalyst and the catalyst can be reused five times without much loss of catalytic activity, this is the best result for non-noble metal catalyzed HMF oxidation to FDCA in the aqueous phase. Structural analysis revealed that surface Mn4+ ions are the active sites and play key roles for the oxidation of HMF in the absence of noble metals. In addition, the reaction mechanism over the MnOx-CeO2 catalyst was also proposed based on the synergistic interaction between Mn and Ce oxides.