TiCl_4-CH_2Cl_2体系的气液平衡计算及应用

Vapor-Liquid Equilibrium Calculation and Application of TiCl_4-CH_2Cl_2 System

采用MOSCED模型,计算得到TiCl4-CH2Cl2二元系中TiCl4和CH2Cl2的无限稀释活度系数分别为1.151和1.114。并根据此数值,采用Wilson模型,计算了TiCl4-CH2Cl2二元系的活度系数。结果表明,TiCl4的活度系数随混合物中TiCl4的摩尔分数的增大而减小,CH2Cl2的活度系数随混合物中TiCl4的摩尔分数的增大而增大。采用试差法根据相平衡原理及TiCl4-CH2Cl2二元系的活度系数计算得到了TiCl4-CH2Cl2二元系的汽液平衡数据,并绘制了TiCl4-CH2Cl2二元系的T-x-y图和y-x图,其误差为10%左右。TiCl4-CH2Cl2二元系的汽液平衡数据表明,TiCl4和CH2Cl2混合物的初步分离可以通过蒸馏实现,而要实现深度分离则需采用精馏的方法,分离所需的理论塔板数为4。TiCl4-CH2Cl2二元系的无限稀释活度系数和拉曼光谱表明,TiCl4和CH2Cl2混合不形成共沸物,混合过程中没有新化合物生成,只是简单的溶解。

The limiting activity coefficient for binary systems of TiCl4-CH2Cl2 was estimated by MOSCED model, and the value was 1. 151 and 1.114 respectively for TiCl4 and CH2Cl2. According to the limiting activity coefficient, the activity coefficient of TiCl4-CH2Cl2 system was calculated by Wilson model. The results showed that the activity coefficient of TiCl4 decreased as the mole fraction of TiCl4 in the mixture increased, but the activity coefficient of CH2 Cl2 increased as the increase of mole fraction of TiCl4 in the mix- ture. According to activity coefficient and theory of phase equilibrium, vapor-liquid equilibrium data of TiCl4-CH2Cl2 system was com- puted by try and error method, and the error was about 10%. Meanwhile, the phase diagram of T-x-y and y-x were drawn. The vapor- liquid equilibrium data indicated that the prefractionation of TiCI4 and CH2 Cl2 could be reached by distillation, and the further separa- tion could be achieved by rectification. The theoretical plate number of rectifying column for further separation of TiCl4 and CH2Cl2 was 4. The Raman spectra and limiting activity coefficient of TiCl4-CH2Cl2 system showed that there was no azeotrope and new species gen- erated when titanium tetrachloride mixed with dichloromethane.