Study On The Catalytic Conversion Of Glucose To 5-hydroxymethyl Furfural By Solid Acid-base Catalyst

With the enrichment of modem material life and the needs of social development,the contradiction between energy supply and demand is becoming increasingly acute,so the exploration of new energy is imperative.Deep processing of glucose has become one of the hotspots of research at home and abroad because of its abundant yield and low price.Conversion of glucose to 5-hydroxymethyl furfural(5-HMF)has good application prospects.5-HMF is a representative biomass-based platform compound,which can be used as intermediates for many reactions,monomers for synthesis of polymer materials,raw materials for synthesis of macrocyclic compounds and so on.Based on the previous research work,717 anion resin and Amberlyst-15 cationic resin are used as solid acid-base catalysts,and the aqueous phase-organic phase is used as a two-phase solvent to establish a highly efficient,environmentally friendly and recyclable reaction system.To summarize the full text,the main work completed is as follows:1.Using glucose as raw material,and starting from the reaction time,reaction temperature,volume ratio of aqueous phase to organic phase,substrate concentration,mass ratio of acid-base catalyst and amount of solid acid-base catalyst,the best results are obtained.The reaction time was 12 h,the reaction temperature was 120“C,the volume ratio of the aqueous phase to the organic phase was 1:2,the substrate concentration was 50%,and the mass ratio of the acid-base catalyst was 3:4.And as the mass of the catalyst increases,the yield of 5-HMF increases,with the highest yield of 54.3%;2.Under the same experimental conditions,5-HMF was prepared from fructose as raw material.The experiment showed that the best effect was obtained by using an acidic catalyst alone,and the yield of 5-HMF was up to 41.9%;3.The reaction kinetics of 5-HMF prepared by glucose was studied in order to provide reference for the optimization of the catalytic system and reaction conditions,and provide a theoretical basis for the clarification of the reaction mechanism.The main and side reactions of glucose dehydration conversion accorded with the first-order reaction rate equation.The activation energy of glucose to 5-HMF was 64.1 kJ·mol-1,and the pre-exponential factor was 1.61×108h-1.The activation energy is 98.1 kJ·mol-1,and the pre-exponential factor is 4.34×1012 h-1.As the reaction temperature increases,the main and side reaction rate constants increase,and the growth rate of k1 is faster than that of k2,which indicates that the increase of reaction temperature promotes the dehydration of glucose to 5-HMF,but also promotes The occurrence of side reactions.4.It has been proved by repeated experiments that the activity of the catalyst is stable and has good reusability.It can be seen from the relationship between temperature and yield that the temperature resistance of 717 anion resin is very good.With the increase of temperature,the yield is stable at about 11.6%.The temperature resistance of Amberlyst-15 cationic resin is poor.When the temperature exceeds 140?,the yield of 5-HMF decreases from 19.1%to 13.5%.The above conclusions were further proved by FT-IR and scanning electron microscopy.5.Titration of acidity and basicity on the surface of catalyst by indicator titration proves that the catalytic activity of catalyst is closely related to the amount of acidity and basicity on its surface,and the higher the amount of acidity or basicity,the higher the catalytic activity.The number of reuse of catalyst has little effect on the activity of catalyst.