Applied Research Of Ionic Liquids In Cellulose Pretreatment Process

With the continuous development of human society, the demand for energy is more and more strong, at present, the fossil energy accounted for a large proportion in the energy structure in the world, however, a large number of unrenewable fossil fuels were exploited and used, including petroleum, coal etc. The world is facing energy crisis and serious environmental pollution problems. Cellulose is environment-friendly energy material, it has no pollution to the environment. The key step is the conversion of cellulose to sugars in the process for using the cellulose. Ionic liquid can play an important role in the pretreatment of cellulose..There is the synthesis of five kinds of ionic liquids in this paper: 1-allyl-3-methylimidazole chloride salt?[Amim]Cl?,N-methylimidazole hydrogen sulfate?[Hmim]HSO₄?,N-methylimidazole dihydric phosphate?[Hmim]H₂PO₄?, N-methyl pyrrolidone hydrosulfate ?[Hnmp]HSO₄?, N-methyl Pyrrolidone dihydrogen phosphate ?[Hnmp]H₂PO₄?.We use 1-allyl-3-methylimidazole chloride salt to dissolve cellulose, then we can obtain regenerated cellulose after centrifugal and washing process by adding anti-solvent,such as distilled water.We can mixed cellulose and acidic ionic liquids, acidic ionic liquid can catalyze the hydrolysis of cellulose to obtain reducing sugar. The total reducing sugar are analyzed by the method of 3,5-dinitrosalicylic acid. We explore the influence of five factors on the yield of reducing sugar, including reaction temperature, the dosage of acidic ionic liquids, amount of water, the type and amount of metal salt, the degree of polymerization of cellulose.The result that N-methyl pyrrolidone hydrosulfate ?[Hnmp]HSO₄? ydrolyzes ellulose is best in four kinds of ionic liquids, the total reducing sugar yield can reach 94.16%after 1.5 hours. The hydrolysis reaction conditions are that the temperature is 100?, the dosage of acidic ionic liquid is 1g, the amount of water is 1g and the dosage of MnCl2 is 0.15g.The experimental results show that a higher temperature?100?? can accelerate the hydrolysis rate of cellulose and get higher TRS yield, which can shorten the reaction time greatly. Meanwhile, the degradation of glucose begins earlier. The hydrolysis rate of cellulose and maximum yield of reducing sugar were not as the same trend as the increasing the dosage of acidic ionic liquids, a large of the amount of ionic liquids will make the degradation rate of reducing sugar accelerated, and reduce the yield of reducing sugar. Too much water can inhibit the hydrolysis of cellulose to reduce the yield of reducing sugar and the rate of hydrolysis of cellulose in the reaction system. The degree of polymerization of cellulose will not only reduce the rate of hydrolysis of cellulose, but also reduce the maximum yield of reducing sugar.