【作者】 吴睿；

【导师】 黄科林；

【作者基本信息】 广西民族大学 ， 应用化学， 2011， 硕士

【摘要】 随着石油、煤等不可再生资源的日益枯竭,纤维素以其来源广泛,储量丰富,以及可再生性引起了人们的广泛关注。特别是通过改性来制备功能化纤维素产品越来越得到人们喜爱。其中纤维素酯作为纤维素一种改性产品已经得到广泛应用。由于纤维素具有较强的分子内和分子间氢键及较高的结晶度,使得其在普通条件下同其他试剂的反应很难进行。近年来发现的新型溶剂离子液体,以其良好热稳定性、极低蒸汽压低、不可燃性引起了人们的青睐,特别是它对纤维素表现出优异的溶解性能,为纤维素均相衍生化反应提供了一个新的思路,大大提高了纤维素的衍生化反应效率和可控性。目前实验室中对于离子液体中纤维素均相酰化技术研究已经日渐成熟,为了更好的控制反应条件,提高反应速率,同时,为纤维素酯离子液体均相法大规模生产提供参考依据,本文以离子液体1-烯丙基-3-甲基咪唑氯盐（AmimCl）为反应媒介,以木浆粕纤维素为原料,研究了离子液体中纤维素与酸酐均相酰化反应的动力学,通过实验考察了不同纤维素初始羟基浓度,不同反应温度对酰化反应速率的影响,结果表明随着离子液体中纤维素羟基浓度的增大和反应温度的增高,纤维素酰化反应的速率都呈增大趋势。通过实验得到了纤维素均相酰化反应的动力学方程,得到了纤维素乙酐酰化及乙酐、丁酐混合酸酐酰化反应的反应级数均为1,表观活化能则分别为19.03 kJ·mol^-1和20.04kJ·mol^-1。最后,本文还研究了离子液体的回收和循环利用,以解决工业大规模生产中离子液体成本较高的问题。本文利用常规减压蒸馏结合分子蒸馏技术对纤维素均相乙酐酰化及均相乙酐、丁酐混合酰化反应后离子液体溶剂进行了回收—循环利用,考察了分子蒸馏过程中各种操作参数如蒸发温度、操作压力和进料速率等对回收离子液体纯度的影响,并通过正交实验优化得到了最佳的回收工艺条件,通过分析表征,结果表明回收的离子液体具有良好的再反应性能,循环利用所得产品同新鲜离子液体所得产品性质一致。更多还原

【Abstract】 With the non-renewable resource becoming more and more exhausted, cellulose has attracted much attention for its plentiful and renewable. Recently cellulose derivatives are more and more popular. For example, cellulose esters are one of the most important cellulose derivatives, which have wide application in our daily life. However, the derivatization of cellulose is very challenging due to its complex inter and inner hydrogen bond and super-molecular structure. Ionic liquid as a novel green and environmentally friendly solvent, have attracted much interest of the researchers for its excellent properties, such as thermal stability, lower melting point, negligible vapor, especially good solubility for cellulose, which provide a new way for cellulose functionalization, and thus increase the efficiency of cellulose derivatization.The homogeneous cellulose esterification is successful in lab, to provide the basis for large scale production, as well as better control of conditions and increase the derivatization rate, using ionic liquid 1-allyl-3-methylimidazolium chloride （AmimCl） as reaction media, cellulose as raw material, the kinetics of homogeneous acylation of cellulose in ionic liquid was studied in this paper. The effect of initial cellulose hydroxyl concentration from 0.21 to 0.85 mol·L^-1 and temperatures from 353 K to 373 K on the acylation rate were measured. Results showed that the acylation rate increases with increasing initial cellulose hydroxyl concentration and reaction temperatures. The reaction kinetic equations were determined based on the experimental data. The reaction order for both acylation by acetic anhydride and by mixture of butyric anhydride and acetic anhydride is first-order, and their apparent activation energies are 19.03kJ·mol^-1 and 20.04kJ·mol^-1 respectively.At last, the recycle and reuse of ionic liquid in the homogeneous cellulose acylation is studied in order to resolve the problem of high cost of IL in the large scale production of cellulose esters. The conventional vacuum distillation and molecular distillation were used to recycle the IL; the effects of the operating parameters, including evaporating temperature, operating pressure, feeding flow rate on the purity of IL were studied. According to andorthogonal experiment data, the optimum conditions of recycling on ILs were obtained. Results showed that the purity of the recycled ILs can reach up to as high as 99.5%, and the product prepared in both fresh and recycled IL is consistent with each other.更多还原