Process simulation and optimization of extractive distillation for separating isopropanol-ethanol from IBE fermentation broth as a gasoline additive

Addressing the downstream processing challenges of the bio-butanol fermentation broth (Isopropanol-Butanol-Ethanol-Water), and producing the isopropanol-ethanol mixture with a mass fraction of ≥ 0.99975 as a high-quality gasoline additive, is crucial for enhancing the overall economy and sustainability of the bio-butanol production process. To obtain the high-purity isopropanol-ethanol mixture, this paper, based on the dehydration-butanol-extractive four column distillation process, proposes a baseline extractive distillation process using a deep eutectic solvent (DES, glycerol: choline chloride = 2:1) as the extractant, termed the extractive distillation-DES basic process. With heat load as optimization target, the extractive distillation-DES basic process was optimized to determine the optimal operating parameters, termed the extractive distillation-DES sensitivity optimization process. Based on the extractive distillation-DES sensitivity optimization process, the particle swarm optimization algorithm was applied to minimize the total annual cost, resulting in the extractive distillation-DES algorithm optimization process. Compared with the extractive distillation-DES basic process, the total load of the extractive distillation-DES sensitivity optimization process is reduced from 1110.15 kW to 856.83 kW (a 22.82 % reduction) and the total annual cost is reduced from 206,744.43 $/Y to 157,726.17 $/Y (a 23.71 % reduction). The total load of the extractive distillation-DES algorithm optimization process is 874.18 kW (a 21.26 % reduction), and the total annual cost is 156,986.01 $/Y (a 24.07 % reduction). • The Deep Eutectic Solvent (DES) was selected over ethylene glycol as a more efficient and eco-friendly extractant. • An Extractive Distillation-DES Basic Process was proposed and optimized via temperature and concentration-composition curves. • After sensitivity analysis and optimization, the Extractive Distillation-DES Sensitivity Optimization Process was devoloped. • The Extractive Distillation-DES Algorithm Optimization Process was developed via particle swarm optimization for parameters. • Both optimized processesdemonstrate superior energy conservation and economy compared with the basic process.