Applied Fundamental Research On Transition Metal Catalysts For The Oxidation Of 5-Hydroxymethylfurfural

Due to the exhaustion of fossil resources,which also cause warming and environmental pollution problems in the process of utilization,the utilization of green renewable biomass resources has received much attention.5-Hydroxymethylfurfural?HMF?obtained from the dehydration of biomass carbohydrates is a key platform compound.It possesses very active chemical properties because it contains aldehyde groups and alcoholic hydroxyl groups.A variety of high-value-added chemicals can be prepared from HMF.Among them,2,5-diformylfuran?DFF?and 2,5-furandicarboxylic acid?FDCA?have broad industrial application prospects as important organic intermediates.However,how to convert HMF to DFF and FDCA with high selectivity is still a challenge.Considering from the problems of precious metal catalysts such as high cost and harsh reaction conditions,this work designed and synthesized a new type of magnetic vanadium-based and manganese oxide nanocatalysts,which were applied to the synthesis of DFF and FDCA from HMF.The main results are as follows:?1?A new type of magnetic vanadium-based catalyst?NH₄·V₃O₈/Fe₃O₄?was prepared by in-situ synthesis,and used for selective oxidation of HMF to DFF.The catalyst structure was characterized by TEM,FT-IR,XRD,ICP,VSM,TG-DTG,etc.The reaction conditions such as solvent,oxidant,vanadium-iron ratio,catalyst dosage,temperature and time were systematically studied.The catalyst exhibits excellent catalytic performance in HMF oxidation,and the HMF conversion can achieve to 95.5%,while the DFF selectivity can reach to82.9%.The catalyst has the advantages of easy magnetic separation and post reaction treatment.?2?MnO₂ nanowires synthesized by the hydrothermal synthesis method were supported on a nitrogen-containing polymer?PDVTA?,and then modified by copper ion to obtain a series of Cu-MnO₂@PDVTA catalyst,which used to catalyze the oxidation of HMF to FDCA.The catalyst structure was characterized by TEM,FT-IR,XRD,XPS and N₂physical adsorption.The mechanism of the catalytic oxidation reaction was mainly explored.It was found that Cu²⁺and Mn O₂ catalyzed HMF oxidation to FDCA mainly through DFF and FFCA as the intermediates.The catalyst realizes high-selective oxidation of HMF to FDCA in an alkali-free system,with a selectivity of FDCA up to 93.9%.The catalyst is still maintains good catalytic activity after repeated use.?3?A series of manganese-based composite oxides were prepared by the solvent combustion method,and used to catalyze the selective oxidation of HMF into FDCA.The effects of reaction conditions such as time,temperature,and oxidant dosage on the catalytic activity were investigated.The experiments results show that the CuMn₂O₄ have the superior catalytic performance in HMF selective oxidation reaction.In the prcent of acetonitrile and tert-butyl hydroperoxide as oxidant,the catalytic reaction can achieve complete conversion of HMF,and the FDCA selectivity reaches to 94.5%.The research is closely integrated with the frontier field of fine conversion of biomass platform compounds,and carries out innovative research in the field of new catalytic materials and reaction processes,which provides an important reference for the design and development of transition metal catalysts during the high-selective conversion of biomass plaform compound HMF.