The Study Of Selective Catalytic Hydrogenation Of Hexose And Its Derivatives

With the rapid development of society,demand on fuel and chemicals is also growing.The hydrogenation products and hydrogenated derivatives of biomass are of great value,which have a wide range of applications in the production of liquild fuels and chemicals.For example,5-hydroxymethylfurfural（HMF）,2,5-bis（hydroxymethyl）furan（BHMF）,2,5-dimethylfuran（DMF）,2,5-dimethyl tetrahydrofuran（DTHF）,γ-valerolactone（GVL）and 5-hydroxy-2-pentone（HPT）,derived from lignocellulose by multistep chemistry procedures,are identified as important platform molecules.Research for catalyzing conversion of hexose into platform molecules with high selectivity was a hot field.The"one pot"strategy is fairly important way in the preparation of the bio-based platform molecules.With the aim of employing heterogeneous catalytic system to convert hexose into HMF,DMF and BHMF,following studies have been carried out in this paper.（1）M_nH_5-nAlW₁₂O₄₀(M=H,M_nH_5-nAlW₁₂O₄₀,sulfonated ionic liquid salt)catalysts doped with Lewis acid-containing metal elements were synthesized by self-assembly method.Those prepared catalysts were characterized by FT-IR and NH₃-TPD technologies for confirming their chemical and physical properties.The reactions of glucose and fructose converted to HMF were studied in detail,where the reaction conditions including reaction temperature,reaction time,catalyst dosage and type of solvents were optimized.Under the optimized reaction condition（10mg hexose,25 mg catalyst,1.0 mL DMSO,160°C,5 h）,and the maximum HMF yield of 25%could be achieved using glucose as substrate.（2）A series of reduced metal-containing catalysts,such as 5%Pd/Al₂O₃,5%Pd/ZrO₂,5%Pd/TiO₂,5%Pd/MOF,5%Ni/C,5%Co/C,5%Ru/C,5%Pt/C,4%Pd-1%Ni/C and4%Pd-1%Co/C,were prapered successfully by impregnation method.Based on the results from the preliminary activity tests,the multifunctional Pd/C-TMS and Pd/C-TMS-HSO₃ were successfully prepared by the post-grafting method,and the detailed characterization was performed.Employing PMHS（polymethylhydrosiloxane）as a hydrogen source and n-butyl alcohol as the solvent,92%yield of DMF was achieved from fructose at 120°C for 1.5 h.The reaction system had a good level of generality and was applicable for conversion of glucose,sucrose and cellobiose into DMF.（3）The application of low-cost commercial KF in conversion of HMF and fructose to BHMF was investigated systematically.As high as 95%and 98%BHMF yields accompanied with 100%selectivity could be obtained from HMF with an individual KF as catalyst at 25oC for 6 h and 80oC for 1 h,respectively.A good BHMF yield of 88%could be also achieved from fructose through a two steps by virtue of using combined catalysts of Amberlyst-15 and KF.