【作者】 李洪玲；

【导师】 田宜灵；

【作者基本信息】 天津大学 ， 物理化学， 2010， 博士

【摘要】 二氧化碳（CO₂）是主要的温室气体,是使全球变暖的重要原因,低碳经济是人们的共识。然而,目前,我国以石化燃料的能源占主导地位,利用过程排放出大量的二氧化碳。如何变废为宝,开发利用CO₂备受关注。超临界二氧化碳（SC-CO₂）具有许多特殊的优良特性使得它在超临界萃取、天然产物的提取、各种化学反应、材料化学等方面得到应用。当SC-CO₂作为萃取剂使用时,需加入少量的醇、酯类以提高其溶解能力。本文对超临界二氧化碳分别与丙酸甲酯、丙酸丙酯、丁酸乙酯和碳酸丙烯酯组成的四个二元系统进行了高压下的相平衡研究以及临界区的确定,以期对含超临界二氧化碳系统的相平衡具有指导意义。本文利用实验室自行设计的国内第一套带石英可视窗的可变体积高压釜,采用静态分析法测定了一系列温度下SC-CO₂分别与丙酸甲酯、丙酸丙酯、丁酸乙酯、碳酸丙烯酯构成的二元系统的高压气液相平衡组成、相密度、摩尔体积。结果表明SC-CO₂在四种酯中均具有较好的溶解度。相同温度下,气相中SC-CO₂的含量随着压力的增大而减小,液相中SC-CO₂的含量随着压力的增大而增大。相同压力下,酯在SC-CO 2中的溶解度与SC-CO₂在液相的溶解度随温度的变化趋势不同,即CO₂在酯中溶解度随温度的升高逐渐减小,而酯在CO₂中溶解度则随温度的升高而逐渐增大。选择PR和PRSV方程分别与Van der Waals-1型、Van der Waals-2型、Margules型混合规则和活度系数表达的混合规则搭配成不同的计算方法,并对上述二元高压GLE实验数据进行优化计算,系统地分析了状态方程、混合规则、回归方法等对计算结果的影响。结果表明,PRSV方程与var der waals型混合规则组成的方法、PR方程与活度系数表达的混合规则组成的方法的计算效果均较好。另外,利用Peng- Robinson状态方程对气体进行修正,拟合得到四个系统在在313、333、353和373 K下的f1 - x1曲线,计算得到了不同温度条件下的Henry系数;利用Gibbs-Helmholtz方程和不同等压条件下的T - x1数据,通过拟和计算得到CO₂在丙酸甲酯、丙酸丙酯、和碳酸丙烯酯溶解过程中摩尔溶解焓Δsol Hm,1和摩尔溶解熵ΔsolS_m,1。更多还原

【Abstract】 Carbon dioxide （CO₂） is an main kind of greenhouse gases, is an important reason for global warming. Low-carbon economy is the consensus of the people,but at present, fossil fuel energy dominate the use of large amounts of carbon dioxide emissions from the process. How to turn waste into wealth, development and utilization of CO 2 cause for concern. Supercritical carbon dioxide （SC-CO₂） has many special characters, which make it was used in supercritical extraction, extraction of natural products, various chemical reactions, material chemistry. When SC-CO₂ is used as extracting agent, a small amount of alcohol or esters required to improve its solubility. In this paper, High-pressure vapor-liquid equilibrium data for the binary systems of CO₂ +methyl propionate （MP）, CO₂ + propyl propionate （PP）, CO₂ + ethyl butyrate （EB） and CO₂ + propylene carbonate （PC） were measured,respectively.A set of variable-volume autoclave with a quartz window has been used for experimental determination. High-pressure vapor-liquid equilibrium data （including mole fractions, density, mole volume and vapor-liquid ratio of the liquid phase and the vapor phase） of the four binary Systems have been measured at different temperatures and pressures with isothermal static analytical method.The experimental results show that the solubilities of SC-CO₂ are greater in the four esters.At the same temperature, the mole fractions of esters in vapor increases and the mole fractions of SC-CO₂ in liquid increase as the pressures were increased. At the same pressure, the effects of temperature on solubilities for esters and SC-CO₂ are different. The solubility of SC-CO₂ in the esters decreased,and the solubility of esters in SC-CO₂ increases.The high-pressure GLE data are also calculated with different methods for above four systems.The PR, PRSV and four different mixing rules are used.The Suitability and accuracy of those EOSs are also been discussed.The results show that PRSV equation with var der waals mixing rules, PR equation with the activity coefficient mixing rules are in good agreement.In addition, Henry equation was modified by Peng-Robinson equation. f1 - x1 curves and Henry coefficients of the four systems at the 313 K, 333 K, 353 K and 373 K were obtained by the modified Henry law. Dissolution molar enthalpyΔsol Hm and dissolution molar entropyΔsolSm ofCO₂ in the esters at different temperature were also calculated.更多还原