Construction Of Multifunctional Solid Catalysts And Study Of Their Catalytic Activities For Carbohydrate Conversion To 5-HMF And FDCA

Seeking for green renewable energy has become an urgent problem to be solved for researchers owing to the fact that the traditional fossil energy with limited and non-renewable reserves cannot meet the requirements of the rapid development of contemporary industry.Biomass energy has drawn extensive attention due to their characteristics such as abundant source,inexpensive and economy,green and environmental protection.A series of biomass-based energy chemicals are mainly synthesizedthroughthemostcarbohydratesofbiomass,suchas5-hydroxymethylfurfural?5-HMF?and its derivatives 2,5-Furadicarboxylic acid?FDCA?have play a major part in application and become research hotspots in the current energy field.Chemical catalysis is the main research direction for the conversion of carbohydrates to 5-HMF and FDCA at present.The catalyst has a very important influence on the yield of 5-HMF and FDCA in the reaction system.Therefore,the design of a novel and high catalytic activity catalyst is an important problem in current research.Porous catalysts are widely used in the field of catalysis because of their large specific surface area,high porosity,easy separation of product,and low corrosivity to equipment.At present,the yield of 5-HMF and FDCA prepared directly from carbohydrates are insufficient,which are often manifested in the multi-step catalytic reaction involved,and there are many intermediate products.However,the porous catalysts with a single active site are difficult to achieve the target of the product with high selectivity.This paper aims to synthesize a strand of multifunctional solid catalysts to increase the yield of 5-HMF and FDCA.The physicochemical properties of multifunctional solid catalysts were determined and analyzed by various characterization methods,and the effects of various catalytic reaction factors on the yield of 5-HMF and FDCA were explored.The main research contents are as follows:?1?The acid-base bifunctionalized composite catalysts preparation of UiO-66-SO₃H-NH₂ supported on polyvinylidene fluoride?PVDF?and their catalytic conversion of glucose to 5-HMFFirstly,PVDF was modified by grafting polydopamine?PDA?.Then the acid-base bifunctionalized composite catalysts UiO-66-SO₃H-NH₂/PVDF@PDA were synthesized by hydrothermal method.The surface area was 351.3 m² g^-1;acidity and alkalinity were 1.34 mmol g^-1 and 0.67 mmol g^-1,respectively.The composite catalyst was used to the preparation of 5-HMF from glucose.The optimum reaction conditions were as follows:reaction temperature was 120?,the amount of catalyst was 0.06 g,the reaction was continued for 120 min,and the highest yield of 5-HMF was 74.3%.?2?The hierarchical porous acid-base bifunctionalized composite catalysts preparation of UiO-66-NH₂ supported on PHS-SO₃H and their catalytic conversion of cellulose to 5-HMFPoly-Pickering HIPEs?PHs?was obtained by thermally initiated polymerization of Pickering High Internal Phase Emulsions?Pickering HIPEs?template method in order to solve the problem that the carrier had no active sites in the surface and the size of the reaction substrate cellulose was difficult to contact with the active sites in the meso/micropores.PHs-SO₃H was obtained by sulfonation of concentrated sulfuric acid.The hierarchical porous acid-base bifunctionalized composite catalyst PHs-SO₃H@UiO-66-NH₂ was successfully prepared by hydrothermal method.The specific surface area and pore volume of the catalyst were 255.4 m² g^-1 and 0.26 cm³g^-1,respectively;and the acidity and alkalinity were 5.40 mmol g^-1 and 1.49 mol g^-1,respectively.It was used in the catalytical conversion of cellulose to 5-HMF.Reaction temperature was 120?,the amount of catalyst was 0.03 g,the reaction was carried out for 60 min,and an optimum yield of 5-HMF was 49.6%.?3?The multifunctional solid catalysts preparation of gold-palladium nanoparticle supported on NCP and its selective oxidation of 5-HMF to FDCAFor the sake of meeting the concept of green environmental protection and reducing the damage caused by alkaline solvents to equipment and environment,the porous polymer PHs and urea were mixed and carbonized to form nitrogen-doped carbon material NCP on the base of the previous experiments,and then the multifunctional solid catalysts NCP@AuxPdy were successfully prepared by sol fixation.Among them,the basicity of NCP@Au_0.75Pd_0.25 was 0.34 mmol g^-1.FDCA was prepared by catalytic oxidation of 5-HMF under alkali-free conditions.The amount of catalyst was 0.1 g,and the reaction was carried out at 110?for 8.0 h.The highest yield of FDCA was 96.2%.