Study On The Preparation Of Imidazolum Based Ionic Liquid And Its Application In Cellulose Hydrolysis

Lignocellulose is a kind of important and abundant renewable materials in nature,. It could be one alternative energy sources of fossil energy by being converted to ethanol. Lignocellulose can't dissolve in most solvents because of its high crystallinity and strong hydrogen bonds existing in the inter- and intra-molecular. There are some shortcomings in traditional solvents which are used to dissolve lignocellulose, such as instability, toxicity, recovery difficulty, and high cost. These factors limit its practical application and development.Ionic liquids have become a research priority as imidazolum based ionic liquids had an excellent solubility of the lignocelluloses. By enzymatic hydrolysis of the regenerated cellulose from ionic liquid, fermentable sugar can be obtained. Therefore, one of the alternative strategies of ethanol production is to use lignocellulosic materials which can resolve the problem of shortage of energy.In my research, [BMIM]Cl and [EMIM]Br were prepared through one step alkylation reaction. Then aqueous halogen ionic liquid solution was flushed through ion exchange column packed with anion exchange resin which was loaded with corresponding anion. [BMIM][HCOO], [BMIM][OAc], [EMIM][HCOO] and [EMIM][OAc] were obtained in high purity.[AMIM]Cl, [BMIM]Cl and 10wt% NaOH aqueous solution were used to pretreat Avicel cellulose, then hydrolysis experiments of the regenerated cellulose and the original cellulose were operated at 40~℃,50~℃and 60~℃, respectively. It can be concluded that hydrolysis rate of regenerated cellulose was 2-3 times higher than that of original cellulose. The cellulase showed the highest reactive activity at 50~℃and the conversion of cellulose to the total reducing sugar was the highest. The lignocelluloses were pretreated at different temperatures ( 80~℃and 120~℃) and different concentrations of cellulose/IL. It was found that higher temperature and dilute cellulose/IL solution were more favourable for the enzymatic hydrolysis of the regenerated cellulose. It also can be found that acetic based ionic liquids nearly have no inactivation on the cellulase activity, so acetic based ionic liquid can be chosen as the best solvent system for lignocellulose.The results of FT-IR and XRD also indicated that the hydrogen bond and the crystallinity of the regenerated cellulose were distinctly decreased from 81.18% to 0%. And at last a possible mechanism of cellulose dissolved in ionic liquid was also proposed.