二氧化碳与2-丁醇二元体系在高压下的亨利系数和偏摩尔体积性质计算

利用固定体积可视高压釜测量出的在323K~353K温度范围内的CO2与2-丁醇二元体系在高压下的汽液相平衡数据,根据Krichevsky-Kasarnovsky方程建立了CO2在液相中的溶解度模型,得到了该二元体系在高压下的亨利系数和CO2在无限稀释溶液中的偏摩尔体积等性质。同时根据偏摩尔体积性质和Peng-Robinson状态方程及Van der Waals-2混合规则来计算该体系在平衡状态下的气、液相的偏摩尔体积。结果表明CO2在2-丁醇中的亨利系数和CO2在无限稀释溶液中的偏摩尔体积均为温度的函数,CO2在2-丁醇中的亨利系数随温度的升高而降低。CO2在无限稀释溶液中的偏摩尔体积∞1V在研究温度下均为负值,其中随温度升高,其绝对值下降。在平衡状态下的气、液相的偏摩尔体积计算结果表明:平衡状态下,液相中CO2与2-丁醇的偏摩尔体积均为正值。气相中不同温度下CO2的偏摩尔体积均为负值,且其绝对值随着压力的增加而越来越大,2-丁醇的偏摩尔体积均为正值。此研究为该体系超临界萃取条件的确立和指导工业化生产提供了理论依据。

Calculation of Henry's coefficient and partial molar volume of carbon dioxide in 2-butanol at elevated pressures

Based on vapor-liquid phase equilibria data for CO2 +2-butanol binary system from 323K to 353K by constant-volume visual high-pressure cell,the solubility model of CO2 in 2-butanol was established with Krichevsky-Kasarnovsky equation.Henry’s coefficients and partial molar volumes of CO2 at infinite dilution were calculated.Meanwhile,Partial molar volumes of CO2 and 2-butanol at equilibrium were calculated from partial molar volumes properties together with Peng-Robinson equation of state and Van der Waals-2 mixed rule.The results showed that Henry’s coefficients and partial molar volumes of CO2 at infinite dilution were both the function of temperature,and Henry’s coefficients decreased with temperature.The partial molar volumes of CO2 at infinite dilution were negative and the magnitudes decreased with temperature.The calculated effects of partial molar volumes of vapor and liquid phase at equilibrium showed that the partial molar volumes of CO2 and 2-butanol in liquid phase were positive,but in vapor the partial molar volumes of CO2 were negative and the partial molar volumes of 2-butanol were positive.The research provided theoretical basis for deciding supercritical extraction conditions and instructing industrial production.