Azeotropic and Extractive Distillation for Bio-Ethanol Dehydration: Process Design, Simulation, and Cost Analysis
Mihaela Neagu, Marilena Nicolae
Abstract
The global demand for sustainable fuels has intensified interest in bioethanol production. Conventional distillation is limited by the ethanol–water azeotrope at ~95.8 wt.% ethanol, necessitating alternative separation methods. This study presents a technical and economic comparison of bioethanol dehydration via azeotropic distillation using cyclopentane as a novel entrainer and extractive distillation with ethylene glycol. Steady-state simulations were conducted in AVEVA PRO/II v.2024 under identical feed conditions, targeting a final ethanol purity of 99.94 wt.%. Cyclopentane proved effective, producing high-purity ethanol and water streams free of entrainer, while ethylene glycol also achieved comparable purity. Economically, the azeotropic process required ~36.5% higher capital investment due to taller columns, larger condensers, and the entrainer cost, resulting in a total annual cost (TAC) ~25.6% higher than the extractive process. Nevertheless, the azeotropic configuration offers lower operating costs, relying solely on low-pressure steam, and residual cyclopentane in ethanol does not compromise fuel quality, unlike ethylene glycol. The study demonstrates that cyclopentane-based azeotropic distillation is technically viable for fuel-grade ethanol production and provides a quantitative framework for evaluating entrainer selection and process economics, particularly in regions where cyclopentane is available or cost-effective.