Ethanol dehydration is hindered by the azeotropic behavior of the ethanol-water system, requiring efficient and sustainable separation strategies. This study presents process design and sustainability assessment of extractive distillation (ED) using glycol-based solvents (monoethylene glycol, triethylene glycol, and glycerol), integrating thermodynamic modeling, process simulation, techno-economic analysis (TEA), and life-cycle assessment (LCA). Vapor-liquid equilibrium data taken from the literature were correlated using the NRTL, UNIQUAC and Wilson models, all of which showed good agreement with the experimental data. The validated NRTL model was subsequently implemented in the process simulations. The simulations indicate that monoethylene glycol limits ethanol purity to 98.6 wt.% due to thermal constraints, while triethylene glycol and glycerol achieve purities up to 99.4 wt.% with c.a. 97% recovery. Flash-assisted extractive distillation (FED) reduces energy demand relative to conventional ED scheme, with glycerol being the most energy-efficient option. Comparisons with atmospheric distillation followed by ED (ADED) indicate that this scheme is favorable for feeds below 30 wt.% ethanol, while FED becomes superior at higher concentrations. For the FED and ADED options using glycerol, both TEA (Capital and Operating Cost, Levelized Production Cost) and LCA (eighteen environmental impact categories and Cumulative Energy Demand) are conducted for various ethanol feedstock concentrations to assess economic and environmental viability. Overall, glycerol-based configurations demonstrate strong alignment between environmental and economic performance, with ADED preferred for dilute feeds with respect to ethanol concentration and FED emerging as the most favorable option for ethanol-rich streams above 30 wt.%.
Economou et al. (2026) studied this question.