Comparison of Pressure-Swing Distillation and Extractive Distillation Methods for Isopropyl Alcohol/Diisopropyl Ether Separation

In the production of isopropyl alcohol, diisopropyl ether appears as a byproduct. Diisopropyl ether and isopropyl alcohol form a binary minimum-boiling homogeneous azeotrope. In this paper, two methods are explored to achieve the separation of this binary azeotrope: fully heat-integrated pressure-swing distillation and extractive distillation with 2-methoxyethanol as an entrainer. The optimal design and dynamic control of the two processes are investigated, respectively. It is revealed that the fully heat-integrated pressure-swing distillation system offers 5.75% reduction in the total annual cost and 7.97% saving in energy consumption as compared to the extractive distillation system. Moreover, control configurations of both processes performed nicely in maintaining the two products' quality when feed flow rate and composition disturbances are introduced. From the standpoint of dynamic control stability, both processes can be used for DIPE/IPA separation.