【作者】 王宇博；

【导师】 金君素；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2013， 博士

【摘要】 超临界体系相平衡研究对促进新型绿色高效超临界流体科学与技术的应用和发展至关重要。本文基于实验研究,通过对实验现象的观察和实验结果的分析,以分子运动理论为指导,利用量子化学计算及统计力学方法,对固体溶质在超临界流体中相平衡问题进行了系统深入的研究。本文主要研究工作如下：改进、完善了一套利用动态法测定超临界流体相平衡数据的实验装置,并对装置的可靠性进行了验证；应用称重法、紫外分光光度法和气相色谱法对实验数据进行了分析。测定了苯磺酰胺、苯甲酸铵、双酚A、双酚S、对苯二甲酸二甲酯5种固体溶质在超临界C02二元体系中的溶解度；测定了苯磺酰胺、苯甲酸铵两种固体溶质在含夹带剂超临界C02三元体系,以及苯甲酰胺和苯甲酸铵等摩尔混合溶质在超临界C02三元体系中的溶解度。实验测定的压力范围为11.0-21.0MPa；温度范围为308-328K；夹带剂包括乙醇、丙酮、乙二醇、乙酸乙酯；夹带剂的摩尔浓度为0.01-0.04。本文实验获得的相平衡数据尚无报道,故丰富了超临界体系相平衡基础数据库,为超临界流体科学与技术的广泛应用提供理论依据和数据支持。利用分子运动理论,深入阐明压力、温度对溶解度的影响机理；结合分子间相互作用及分子的结构性质,系统分析了实验中不同溶质在超临界C02中溶解度的变化机制,夹带剂的种类和浓度对溶解度的影响,以及在混合溶质体系中溶质间的相互作用对溶解度的影响机理。本文利用Chrastll、A-L、K-J、Tang、S-S、Bartle、M-T、Yu和Gordillo共9种密度型或压力型经验模型对溶质在超临界C02二元体系中溶解度进行了关联,获得了模型的参数,比较了各个模型的平均绝对相对偏差(Average absolute relative deviation, AARD);利用M-T模型评价实验数据的自洽一致性。结果表明,实验数据的自洽一致性良好。利用Chrastll、K-J及Bartle模型计算了溶质在超临界CO2中的溶解热效应。应用Gonzalez、T-G、Sovova及改进Sovova模型关联计算了溶质在含夹带剂超临界CO2三元体系及混合溶质在超临界CO2三元体系中的溶解度,获得各模型参数和计算偏差。结合密度泛函的计算方法,采用Gaussian03程序计算了溶质与超临界CO2分子间,溶质与夹带剂分子间,混合溶质分子间的结合能,并利用分子间结合能进一步阐明了溶质结构、夹带剂对溶解度的影响。根据溶质在超临界流体中的溶解机理,应用理论计算的分子间结合能及溶质和溶剂的特征性质,建立了具有预测功能的溶解度模型。根据本文实验物系的确立方法,选择18种芳香族衍生物固体溶质建立了溶质样本,通过对18种溶质的溶解度数据进行计算,获得了新建溶解度模型的参数；根据溶质样本的建立方法,选择另外10种芳香族衍生物固体溶质,利用新建的溶解度模型预测了上述10种溶质在超临界CO2中的溶解度。通过研究发现,新建模型对10种固体溶质在较高压力(P>13.0MPa)时溶解度的预测值与实验值的平均AARD为17.70%。结果表明,新建溶解度模型具有较强的预测功能、较广的适用范围和较好的计算精度。为了实现不依靠实验数据对溶质在超临界流体中溶解度进行理论预测,本文依据超临界体系相平衡的特点,研究探索了基于统计缔合流体理论(SAFT)计算固体溶质在超临界流体中溶解度的方法,根据文献获得了溶质在固相及超临界相中的能量表达式。利用SAFT模型对文献中10种固体溶质的溶解度数据在一定压力和温度范围内进行了预测计算,并与文献数据进行了对比,计算结果表明利用SAFT模型对10种固体溶质的溶解度预测结果很好(平均AARD为1.42%)。该方法为超临界体系溶解度的理论预测提供了新的思路和方法。本文研究得到国家自然科学基金(21176012)和江苏省自然科学基金(BK2012595)的资助。更多还原

【Abstract】 Phase equilibrium of supercritical fluid system is a key factor in development of supercritical fluid technology. This work makes systematic and theoretical experimental study on the phase equilibrium of solid and supercritical fluid system based on molecular kinetic theory, quantum-chemical calculation and statistical mechanics. The main content of the thesis are as follows:An experimental instrument based on the dynamic method is set up and modified to determine the experimental solubility data of solid in supuercritical system. The reliability of the instrument is verified. Electronic balance weighing, ultraviolet spectrometer and gas chromatography are used to measure the concentration of solid solute. Solubilities of solid solute including benzene sulfonamide, ammonium benzoate, bisphenol A, bisphenol S, dimethyl terephthalate in pure supercritical CO2(SCCO2) are investigated in this work; ternary system including benzene sulfonamide with cosolvent, ammonium benzoate with cosolvent, mixture solute of ammonium benzoate and benzamide in SCCO2are also studied. The experimental temperature is ranging from308to328K over a pressure range of11.0to21.0MPa. Ethanol, acetone ethylene glycol and ethyl acetate are chosen as cosolvent with mole fraction from0.01to0.04. The solubility data obtained in this work are first determined and have not been reported in literature. The determinations make a great contribution to the supercritical phase equilibrium data bases, which provide supporting for the application of supercritical fluid technology.An assumption is proposed based on the theory of molecular motion to investigate the effect of temperature and pressure on the solubility of solutes in supercritical CO2. The difference in solubility between different solute and different cosolvent, the effect of cosolvent molar fraction and mixture solute on solubility are investigated by analysis of molecular structure, and interactions between solute and solvent moleculars.Correlation of9empirical models based on density or pressure, including Chrastll, A-L, K-J, Tang, S-S, Bartle, M-T, Yu and Gordillo are made to experimental data and the parameters of each empirical models are obtained. The average absolute relative deviation (AARD) is used to evaluate9semi-empirical models. The self-consistency of the experimental data is satisfactorily determined by M-T model. The dissolving thermodynamic property of solid solute was calculated by Chrastll, K-J and Bartle models. Experimental solublities in ternary system are correlated by Gonzalez, T-G, Sovova and modified Sovova models. The parameters for each model are obtained and the value of AARD are calculated.The molecular interaction between solute molecule and solvent molecule is calculated by density function theory (DFT) method. GaussianO3procedure is adopted to process the calculation of the interactions between solute and CO2, solute and cosolvent, and solute mixture. The effects of solute structure and cosolvent on solubility are further analyzed by calculation result. According to the mechanism of solid dissolving in SCCO2, a solubility model is proposed through molecular interaction and physicochemical properties of solute and solvent. Data samples including18aromatic compounds are set up as the selection method of solid solute in this work. The parameters in the model are obtained by correlation and regression of available solubility data of18different compounds in SCCO2. Accroding to the same selection criteria of data samples, another10soild solutes are chosen for the prediction calculation by the new model. The calculation solubilities show good aggrement with those in literature under high pressure (P>13.0MPa). The average AARD for10solutes is17.70%, which indicates the new model is of good performance in solubility prediction, broader applicability and high-accuracy.For the purpose of solubility prediction without experimental data, this work makes exploration to build a model based on statistical association fluid theory (SAFT) to predict solubility of solid solute in SCCO2. The energy expressions for the solute in solid phase and supercritical phase are established according to references respectively. The solubility predictions for10solid solutes in SCCO2are investigated by SAFT model. The solubility predictions show fairly good accuracy, the average AARD%for10solutes is1.42%. SAFT model could provide innovative research idea and method for theoretical prediction of solublity of solute in SCCO2.This research is financially supported by the National Natural Science Foundation of China (No.21176012), the Natural Science Foundation of Jiangsu Province (No. BK2012595).更多还原