甲醇-乙酸-丙酸多元体系汽液平衡

Vapor-liquid equilibrium of methanol-acetic acid-propionic acid multicomponent system

用新型泵式沸点仪测定了在100kPa下甲醇-乙酸、甲醇-丙酸、乙酸-丙酸3个二元体系以及甲醇-乙酸-丙酸三元系在不同液相组成时的沸点,并用间接法T-p-x(温度、压力和液相摩尔分数)推算了3个二元体系的汽相平衡组成。3个二元体系活度系数分别用Wilson模型、NRTL模型、Margules模型和van Laar模型进行关联,用最小二乘法求出了它们的液相活度系数模型参数,同时,用这些模型参数来计算它们的汽相摩尔分数。所得的液相活度系数来计算3个二元体系的过量吉布斯自由能函数,且所研究的所有体系中各组分之间不存在共沸点。用3个二元体系Wilson模型参数对所测的三元体系数据进行关联,建立该系统汽液平衡的热力学模型并计算平衡时的汽相摩尔分数和泡点温度。由面积积分法检验这些模型参数计算的3个二元体系相平衡数据,得到很好的热力学一致性。

The isobaric vapor-liquid equilibrium （VLE） data at 100 kPa for 3 binary systems containing methanol-acetic acid,methanol-propionic acid and acetic acid-propionic acid and a ternary system containing methanol-acetic acid-propionic acid were determined with different liquid phase compositions by using a novel pump-ebulliometer. The vapor phase equilibrium compositions of 3 binary systems were calculated through T-p-x temperature,pressure and liquid-phase molar fraction based on the indirect method. The activity coefficients of 3 binary systems were correlated with the Wilson,NRTL,Margules and van Laar models through the least square method,and these model parameters in turn were used to calculate vapor phase molar fraction. The activity coefficients obtained were used to calculate the excess Gibbs function for the 3 binary systems,and no azeotropes exist among the components of all the systems. The VLE data of the ternary system were correlated based on Wilson model parameters of the 3 binary systems in order to build the thermodynamic model of VLE for the ternary system and obtain the vapor phase molar fraction and the calculated bubble points. The calculated bubble points with the model parameters of activity coefficients are in good agreement with the experimental data. The thermodynamic consistency of the experimental data for the 3 binary systems checked by area test method is satisfactory.