Self-developed Fabrication Of Manganese Oxides Microtubes With Efficient Catalytic Performance For The Selective Oxidation Of 5-Hydroxymethylfurfural

With the rapid development of industry,the reserves of traditional fossil resources are continuously decreasing.Biomass is the only renewable resource rich in carbon in the nature,and it can be used to replace traditional fossil fuels.For one of the biomass derived products,HMF is considered as biomass platform to prepare other high valued chemical compounds.2,5-diformylfuran(DFF)is a product for the oxidation of HMF,can be used for polymer materials,macrocyclic ligand,antifungal agent,etc.At present,the catalysts in the reaction system of HMF oxidation to DFF has the problems of complicated preparation,easy generation of toxic substances,easy aggregation and leaching,and high cost.This paper synthesized a manganese oxide catalyst by a simple hydrothermal method to catalyze the selective oxidation of HMF with molecular oxygen as oxidants.The composition and morphology of MnOx were analyzed by characterization techniques,and the catalytic performance was tested.A new type of manganese oxides microtubes(MnOx)were prepared in situ formation,which includes chemical conversion and the physical Oswald ripening.The synergistic interaction between β-MnO2 and α-Mn2O3 phases and the high manganese oxidation state Mn4+ as the active species make MnOx microtubes show high catalytic activity for selective aerobic oxidation of HMF to DFF.DFF was obtained with high selectivity of 100%under the reaction conditions of 90℃,0.8 MPa O2,and N,N-dimethyformamide as solvent.In addition,the MnOx microtubes catalyst was easy to separate and reuse without any significant loss after the cycle experiments,indicating its excellent reusability and stability.Morever,the reaction mechanism and kinetic study were investigated.The reaction can be fitted as a first-order reaction for HMF,and has a lower activation energy with an 49.39 kJ/mol than other published non-noble catalysts.And the catalyst promotes the reaction through the redox cycle between Mn4+and Mn2+.