Applied Research On Manganese-Based Catalysts For The Selective Oxidation 0f 5-Hydroxymethylfurfural

With the increasing depletion of carbon-based fossil resources such as coal,oil,and natural gas,biomass resources that can be regenerated through photosynthesis have attracted more and more attention.The catalytic transformation of biomass and its derivatives into fine chemical products is the technological commanding height of all scountries.5-Hydroxymethylfurfural（HMF）is an important platform molecule derived from plant biomass.The 2,5-Diformylfuran（DFF）and 2,5-Furandicarboxylic acid（FDCA）obtained by HMF oxidation are both high-value furan-based chemicals.However,because of the diversity of HMF oxidation products,how to prepare DFF and FDCA with high selectivity and reduce the cost of catalysts is a major challenge in this field.In this study,a series of highly active manganese-based non-noble metal heterogeneous catalysts were prepared for the selective oxidation of HMF to DFF or FDCA.The main research contents and results are as follows:（1）A series of vanadium-manganese composite oxide catalysts were prepared using manganese oxalate as the manganese source and ammonium metavanadate as the vanadium source,and their catalytic performance in the HMF oxidation reaction was studied.The properties of the catalyst were characterized by means of X-ray diffffraction（XRD）,Transmission electron microscopy（TEM）and Fourier transform infrared（FI-IR）,and the influence of factors such as the type and amount of catalyst,reaction solvent and reaction time on the reaction were investigated.When the molar ratio of vanadium to manganese is 3:1,the catalyst exhibits good catalytic activity and the main product of HMF oxidation is DFF,and the selectivity can reach 97.2%.The repeatability experiments prove that the catalyst has good stability.（2）The Cu-Mn O₂ catalyst was prepared by hydrothermal synthesis and applied to the selective oxidation of HMF under normal pressure to prepare FDCA.The morphology,crystal phase and thermal stability of the catalyst were characterized by TEM,XRD and Thermogravimetry-difffferential thermal analysis（TG-DTG）,and the effects of different catalysts,solvents and oxidants on the product selectivity were investigated.Under suitable reaction conditions,HMF was almost completely reacted,and the selectivity of FDCA can reach96.3%.When tert-butyl hydroperoxide was used as the oxidant,tert-butanol was the best solvent for this reaction.In addition,the catalyst still maintains good catalytic activity after repeated use for ten times.This research aims at the selective oxidation of HMF to prepare DFF or FDCA,and constructs a new reaction system based on manganese-based catalysts,which will lay the foundation for the design and development of non-noble metal catalysts in the selective catalytic conversion of biomass.