基于分子模拟的共沸物形成与强化分离机
理研究
Study on Formation of Azeotrope and Mechanism of Enhanced Separation Bad on Molecular Simulation
工程领域：化学工程
微信电脑版怎么发朋友圈
作者姓名：张季
指导教师：李洪特聘研究员
企业导师：罗铭芳高级工程师
天津大学化工学院
二零一七年五月本科分数线
独创性声明
本人声明所呈交的学位论文是本人在导师指导下进行的研究工作和取得的研究成果，除了文中特别加以标注和致谢之处外，论文中不包含其他人已经发表或撰写过的研究成果，也不包含为获得天津大学或其他教育机构的学位或证书而使用过的材料。与我一同工作的对本研究所做的任何贡献均已在论文中作了明确的说明并表示了谢意。
甲午战争观后感
学位论文作者签名：签字日期：年月日
学位论文版权使用授权书
本学位论文作者完全了解天津大学有关保留、使用学位论文的规定。特授权天津大学可以将学位论文的全部或部分内容编入有关数据库进行检索，并采用影印、缩印或扫描等复制手段保存、汇编以供查阅和借阅。同意学校向国家有关部门或机构送交论文的复印件和磁盘。杨二嫂的人物形象
（保密的学位论文在解密后适用本授权说明）
学位论文作者签名：导师签名：
签字日期：年月日签字日期：年月日
南浔旅游摘要
衣服牌子标志图片相平衡与化工单元操作过程有着密不可分的联系，作为具有特殊相行为的共沸物体系，不能通过普通的精馏方式将其分离。萃取精馏是一种常用的热分离方法，通过加入高沸点的萃取剂改变共沸组分的相对挥发度，进而实现共沸物的分离。目前，共沸物形成及其与萃取剂作用的微观机理均尚不明确，这极大地限制了热分离方法在共沸物分离领域的应用。近年来随着计算机技术和统计力学的快速发展，应用分子模拟方法研究相平衡现象及分离机理已成为热点。
本文以乙酸乙酯-乙醇（甲醇）共沸体系为例，首先基于量子化学方法计算了TaPPE-UA力场中缺少的乙酸乙酯分子二面角扭转项参数，通过计算乙酸乙酯纯组分的汽液共存曲线及蒸发焓、饱和蒸气压等性质，验证补充参数后力场的准确性和适用性。采用吉布斯系综蒙特卡罗(GEMC)方法结合TaPPE-UA力场模拟计算了在70kPa、300kPa以及500kPa不同压力下乙酸乙酯-乙醇（甲醇）的相平衡数据，通过比较模拟数据与实验数据可知该方法能够很好的描述该共沸体系的相平衡数据。在此基础上，采用径向分布函数方法分析了不同压力下共沸点处以及等浓度处乙酸乙酯-乙醇（甲醇）的平衡液相微观结构，结果表明醇分子间的氢键自缔合作用较强，乙酸乙酯分子与醇分子间的氢键交叉缔合作用较弱。当压力增加时，醇分子的聚集密度减小，醇分子间的氢键缔合作用减弱，这正解释了升高压力乙酸乙酯-乙醇（甲醇）共沸体系共沸点处醇的摩尔组成增大的现象。
进一步基于密度泛函理论，探究了1-辛基-3-甲基咪唑四氟硼酸盐([OMIM][BF4])离子液体作为萃取剂分离乙酸乙酯-乙醇共沸体系的微观作用机理。通过采用红外光谱、相互作用能以及约化密度梯度(RDG)
分析，得到乙酸乙酯与乙醇分子间的相互作用较小，离子液体加入后，乙酸乙酯分子易与阳离子发生作用，乙醇分子易与阴离子发生作用，从整体上看离子对与乙醇分子间的作用较强，离子对将乙醇分子“绑定”，自由的乙醇分子数量减少，使得过量的乙酸乙酯分子从乙醇分子中析出，共沸物的组成发生变化，进而将共沸物分离，通过离子对与共沸组分分子作用机理的研究可以为萃取剂的筛选和设计提供理论指导。
关键词：Gibbs系综蒙特卡罗方法；共沸物；汽液相平衡；径向分布函数；微观结构；分离机理
I
荷花的用途II
ABSTRACT
Pha equilibrium and chemical unit operation for paration are inextricably linked. As an azeotrope with special pha behavior, it can not be parated by ordinary distillation method. Extractive distillation is a thermal paration method，which is ud commonly The azeotrope is often parated by extractive distillation through adding a high boiling entrainer and changing the relative volatilization of the azeotropic components. At prent, the mechanisms of the azeotropic formation
and its interaction with the entrainment are not clear, and the design of azeotropic paration has been greatly limited. In recent years, with the rapid development of computing technology and statistical mechanics, the application of molecular simulation method to study the pha equilibrium and paration mechanism has become a hot topic.
舞曲大全The ethyl acetate-ethanol (methanol) were lected as the rearch system. Firstly, the missing dihedral parameters of ethyl acetate molecule in the TaPPE-UA field were calculated bad on the quantum chemical method. The accuracy and applicability of this force field were verified by calculating the vapor-liquid coexistence curve, the enthalpy of evaporation and the saturated vapor pressure of the pure ethyl acetate. Moreover, the pha equilibrium of ethyl acetate ethanol (methanol) were simulated by this force field using GEMC method at 70 kPa, 300 kPa and 500 kPa. The results calculated are in good agreement with experimental data and the simulation reproduced the azeotropic behavior of this mixture with an excellent qualitative and quantitative agreements. Besides, the equilibrium liquid pha microstructures of ethyl acetate-ethanol (methanol) were analyzed by radial distribution function method at the azeotropic points and equal concentration points of different pressures. It was found that autoassociation of hydrogen bonds between alcohol molecules was stronger than cross association of hydrogen bonds between ethyl acetate molecule a
nd alcohol molecule. When the pressure increas, the aggregation density of the alcohol molecules decreas, so the association hydrogen bonds between the alcohol molecules decreas. It is explained the reason why the
III
