Energy-saving separation of isobutanol/ethanol/water by extractive distillation with deep eutectic solvents

Abstract

To recycle isobutanol and ethanol from wastewater, different extractive distillation flowsheets with different entrainers are proposed. Firstly, the entrainers glycerol (GI), ethylene glycol (EG) and different deep eutectic solvents (DESs) are compared from the perspective of relative volatility and quantum chemical calculation. Subsequently, the indirect extractive distillation (IED) process and direct extractive distillation (DED) process with ChCl/GI(1:2) or EG as entrainer are studied and optimized using the NSGA-II method. Moreover, heat integration is utilized to optimize energy efficiency. The results reveal that the ChCl/GI(1:2) processes are more environmentally friendly and economical than EG processes. The heat integrated indirect extractive distillation process (IED) with ChCl/GI(1:2) entrainer demonstrates the most promising process, with a reduction of 35.93% in TAC and 34.89% in CO₂ emissions compared to the IED-EG process.