Purification of methyl isobutyl ketone via dividing wall column with an internal boiling point of a heterogeneous azeotrope

Abstract

Methyl isobutyl ketone (MIBK) is an important chemical product used in many fields and is mostly made by the acetone one-step method. It is difficult to extract high-purity MIBK from the reactants where complex azeotropes form, thus leading to traditional MIBK separation process at high energy cost and investments. In this study, a new separation process based on dividing wall column, HA-DWC-U, was developed considering the heterogeneous azeotrope with an internal boiling point. First, thermodynamic research was performed to assure the accuracy of the physical properties. The NRTL and UNIQUAC models were compared, of which some model parameters were regressed from experimental data, and two binary parameter data sets were set for the VLE and LLE calculations. Then, steady-state simulation and optimization of the traditional process and HA-DWC-U were performed, in which continuous variables were optimized in the inner loop using the sequential quadratic programing (SQP) method, while discrete variables were optimized in the outer loop using sensitivity analysis method. Remarkable, the results show that HA-DWC-U has obvious advantages over the traditional separation process, including 18.47% savings in total utility cost and 17.86% savings in total annual cost.