Designing an extractive distillation process for separating a heterogeneous mixture of isopropyl alcohol, isopropyl acetate, and water

Abstract

This study investigates the separation of the challenging ternary mixture of isopropyl acetate (IPAC), isopropyl alcohol (IPA), and water, which forms four azeotropes. Two extractive distillation processes are proposed and designed: conventional extractive distillation with double entrainer (D-CED) and side-stream extractive distillation with double entrainer (D-SSED), using glycerol as an eco-friendly solvent to enhance the relative volatility among the components. The innovation of this work is the systematic application and comparison of double-entrainer CED and an advanced side-stream configuration for this specific four-azeotrope system using glycerol as a green solvent. The processes were thermodynamically modeled using the NRTL model, simulated in Aspen Plus, and optimized using a genetic algorithm to reduce the total annual cost (TAC) and CO2 emissions. Important parameters such as the number of trays, feed tray position, reflux ratio, and entrainer flow rate were optimized. A novel double-entrainer D-SSED configuration is proposed for this azeotropic system, which demonstrated superior economic and environmental performance, resulting in a 3.5% reduction in TAC and a 4.2% reduction in CO2 emissions compared to the D-CED process. In addition, heat integration and solvent temperature effects are systematically investigated, and a heat exchanger is integrated to reduce energy consumption by minimizing reboiler and cooler duties. This study highlights the effectiveness of the proposed D-SSED configuration as a sustainable and cost-efficient approach for separating complex azeotropic mixtures.