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To synthesize simple and efficient catalysts and their application in catalytic conversion of biomass platform compounds to prepare high value-added chemicals has always been the focus of researchers. In this paper, a catalyst composed of iron, manganese, copper and Schiff base ligand derived from amantadine salicylaldehyde was in-situconstructed to catalyze the selective oxidation of 5-hydroxymethylfurfural (HMF) to prepare 5-formyl-2-furancarboxylic acid (FFCA). The ligands and complexes were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (FT-IR) and single crystal diffraction, and the reaction conditions such as oxidation reaction time, reaction temperature, molar ratio of MnCl2·4H2O to ligand, oxidant and catalyst dosage, etc, were optimized. Under the optimized conditions, 100% conversion of HMF and the FFCA with a yield of 52.1% can be obtained. Finally, on the basis of the reaction results, the HMF oxidation reaction process catalyzed by Mn metal complexes was analyzed.

MnO2with different crystal structures was used to catalyze the oxidation reaction of 5-hydroxylmethylfurfural (HMF), and α-MnO2exhibited the highest catalytic activity. Magnetic MnO2-Fe3O4oxides were prepared by α-MnO2and Fe3O4and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption of NH3/CO2(NH3/CO2-TPD) and Fourier transform infrared reflection spectra of pyridine adsorption (Py-FTIR). The results showed that the composite catalyst still maintained the basic structure of α-MnO2and Fe3O4, whereas the number of active center Mn4+·O2−ion pair increased compared with α-MnO2and Fe3O4, which significantly improved the catalytic activity on HMF oxidation reaction. The reaction conditions of HMF oxidation to 2,5-furandicarboxylic acid (FDCA) were optimized. The composite oxide Mn8Fe3Oxshowed the best catalytic performance for HMF oxidation. HMF could be completely converted, with 76.9% of FDCA yield under the optimal conditions.