CIESC Journal

• 化工学报 • 上一篇    下一篇

渗透汽化-酯化反应耦联膜过程动力学模型

李雪辉,王乐夫,孙琳   

  1. 华南理工大学化学工程系!广州510640,华南理工大学化学工程系!广州510640,广东工业大学数理系!广州510643
  • 出版日期:2000-04-25 发布日期:2000-04-25

KINETIC MODELING OF PERVAPORATION-ESTERIFICATIONCOUPLED MEMBRANE PROCESS

Li Xuehui and Wang Lefu(Department of Chemical Engineering, South ChinaUniversity of Technology, Guangzhou 510640)Sun Lin(Department of Mathmetics and Physics,GuangdongUniversity of Technology,Guangzhou 510643)   

  • Online:2000-04-25 Published:2000-04-25

摘要: 建立了渗透汽化 -酯化反应耦联复合膜反应器过程动力学模型及测量复合膜渗透率的方法 .该动力学模型较系统地考虑了复合膜反应器中可能影响酯化反应化学平衡移动的各种因素 .研究结果表明 ,模型的模拟结果能很好地与实验结果相吻合 .

Abstract: Pervaporation is unique among membrane separations, involving a change of phase to achieve separation. Its most potential application is the use of pervaporation process to drive an equilibrated reaction, such as esterification, etherification, synthesis of methyl isobutyl ketone. In a membrane reactor, pervaporation has been applied to the continuous removal of water from esterification reaction mixture. For a special reaction system, if the kinetic model is established,the relationship between reagent conversion, product yield and water concentration can all be described by it at the same time. It can provide the theoretical basis for process economic evaluation,defining the optimum reaction conditions and for predicting the reaction system status. For the esterification coupled pervaporation membrane reactor, many studies have been done concerning the coupled membrane process kinetic model. But, some important factors, such as reaction-separation temperature and feed water concentration which are always unavoidable in industries were not taken into consideration in these kinetic models. On the other hand,a standard method for defining water permeance has not been established yet. So, in these studies, the established kinetic models can only simulate the coupled membrane process under limited conditions. In this study, pervaporation separation of ethanol-water azeotropic mixture and the experiments of pervaporation coupled esterification are carried out in a batch reactor with the membrane area of 19.2 cm~2. PPVA/PAN composite membrane is prepared and used in the coupled membrane reactor. Through combining the kinetic equation of esterification and the kinetic equation of pervaporation, a kinetic model for esterification-pervaporation coupled composite membrane process is established:dXdt=n_0kV-1.8×10~-5n_0 (X-Y)(1-X)(R_1-X)-XK(Y+R_2) dYdt=dXdt-pS(X+R_2)V-1.8×10~-5n_0 (X-Y)exp-E_aRT All the factors that may influence the shift of esterification chemical equilibrium are all taken into consideration in this kinetic model. At the same time, the method for defining the modeling parameter, p, is determined. The above equations can be solved numerically by using a personal computer and the Runge-Kutta method to yield the concentrations of different species in the reactor under different reaction conditions and times. The studying results showed that the experimental data and the simulation data obtained from the same reaction condition are in good agreement. Therefore we can be concluded that the established kinetic model of pervaporation-esterification coupled composite membrane reactor can predict the reaction-separation process exactly.

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