Energy-Efficient and Low-Carbon Recovery of Organic Compounds via Electrified Deep Eutectic Solvent-Based Extractive Distillation

Abstract Methyl ethyl ketone (MEK) and ethanol (EtOH) form an azeotrope at atmospheric pressure, making their effective separation and recovery by conventional distillation difficult. In this study, two imidazole-based deep eutectic solvents (DESs) were selected as entrainers for extractive distillation of the MEK-EtOH azeotrope. Their separation performance was evaluated by ternary vapor-liquid equilibrium (VLE) experiments, and the data were correlated using the non-random two-liquid (NRTL) model. Quantum chemical calculations revealed that strong hydrogen-bonding interactions between the DESs and azeotropic components are essential for efficient separation. Extractive distillation processes using dimethyl sulfoxide (DMSO) and the best-performing DES as entrainers were designed and optimized via multi-objective optimization coupled with multi-criteria decision-making. Life cycle assessment was performed using Eco-indicator 99 (EI-99). Compared with the DMSO-based process, the DES-based process achieved lower total annual cost (TAC), CO2 emissions (ECO2), and EI-99 score, but exhibited a relatively lower thermodynamic efficiency. Compared with the non-electrified DES-based process, the flash vapor compression heat pump (FVCHP)-electrified DES-based process reduced TAC, ECO2, and EI-99 by 5.81%, 43.64%, and 50.71%, respectively. This study offers a low-carbon and economical strategy for azeotrope separation.