Synthesis Of Deep Eutectic Solvents And Its Catalytic Hydrolysis Of Cellulose

Nowadays,there are problems of environmental pollution caused by irrational use of cellulose,how to utilize cellulose green and efficient has attracted worldwide attention.At present,biomass can produce various chemicals,and the conversion methods are confined in application due to poor stability of the catalytic system,lower yield,lower selectivity and ease environmental pollution.This research aims to improve the stability and selectivity of the catalytic system,choline-based deep eutectic solvents(DES)and amino acid-based deep eutectic solvents were designed and synthesized to study the physical and chemical properties,formation mechanism and catalytic hydrolysis mechanism of cellulose.The main research contents and results are as follows:Choline chloride(Ch Cl),triethylallyl ammonium chloride([ATEAm][Cl]),p-toluenesulfonic acid(Ts OH)and methanesulfonic acid(MSA)were used as raw materials to synthesize a series of Ch Cl-Ts OH,Ch Cl-MSA and [ATEAm][Cl]-Ts OH three choline-based DESs.With L-proline(L-Pro),L-lysine(L-Lys),L-glutamic acid(L-Glu),ethylene glycol(EG),p-toluenesulfonic acid and methanesulfonic acid,a series of five amino acid-based DES,L-Pro/EG,L-Lys/EG,L-Pro/Ts OH,L-Glu/Gly and L-Pro/MSA,were synthesized,respectively.The physical and chemical properties of DESs were investigated.and the results showed that DES has good thermal stability,strong acidity and high water content,which provides a good environment for the subsequent cellulose hydrolysis process and the results showed that DESs have good thermal stability,strong acidity and high water content,which provides a good environment for the subsequent cellulose hydrolysis process.Choline-based DESs were utilized to catalyze the hydrolysis of cellulose to produce TRS.In the application,the influence of the DES type,temperature,time,and cellulose concentration in choline-based DES on the catalytic hydrolysis of cellulose to TRS was investigated.[ATEAm][Cl]-Ts OH DES had the best hydrolysis efficiency of cellulose conversion,which was higher than that of conversion efficiency of Ch CI-Ts OH DES and Ch CI-MSA DES.Under the optimal process parameters,the highest conversion rate of cellulose was 85.3%,and the highest TRS yield was 42.8%,but there are problems such as poor recyclability,poor stability and a low yield of the reaction system.Amino acid-based DESs were used to catalyze the hydrolysis of cellulose to produce TRS,and the introduction of the catalyst Lewis acid ferric trichloride hexahydrate(Fe Cl3.6H2O)could improve the yield significantly.Under the optimal conditions for the hydrolysis of cellulose in the L-Pro/EG/Fe Cl3.6H2 O system,the molar ratio of 1:1:2,the reaction time of 120 minutes and the reaction temperature of 120 °C,the cellulose conversion rate could achieve 85.6%,and TRS production rate was 66.7%.Good catalytic stability of amino acid-based DESs makes the conversion process greener,provides a technical reference for the engineering application of this technology,and has certain practical value for environmental protection.