Separation of n-hexane–ethyl acetate mixtures by azeotropic batch distillation with heterogeneous entrainers

Abstract

Tel: (33) 5 62 88 58 26 ; fax: (33) 5 62 88 58 29Accepted for publication in Chemical Engineering & Processing Abstract.In this article, a systematic study of the separation of the n-hexane -ethyl acetate mixture with an entrainer by heterogeneous azeotropic batch distillation is performed. Based upon the thermodynamic behaviour of the ternary mixtures, potential entrainers partially miscible with one or two original azeotropic components are chosen. In all cases, the entrainer adds a heterogeneous binary or ternary azeotrope that is the lowest boiling point in the ternary diagram. Therefore, it leaves the column by the overhead stream which is subcooled to get two liquid phases in the decanter. The phase with the highest amount of the original component is removed as distillate product whereas the entrainer -rich phase is continuously refluxed to the column. Considering methanol, acetonitrile, water and nitromethane as heterogeneous entrainers, screening was performed based on the 2 composition of the unstable heteroazeotropic mixture, the ratio of both liquid phases in the condensed top vapour and the purity of the distillate product determined by the liquidliquid envelope at the decanter temperature. The process feasibility analysis is validated by using rigorous simulation with the batch process simulator ProSimBatch. Simulation results are then corroborated in a bench experimental column for the selected entrainer, showing several advantages of heterogeneous batch distillation compared to homogeneous systems.

Liquid–Liquid Separation of an Azeotropic Mixture (Hexane/Ethyl Acetate) with Imidazolium-Based Ionic Liquids

“…Conventional distillation is not a suitable technique to separate ethyl acetate from hexane because of the formation of minimum azeotropic mixtures, and it is not economically feasible. Azeotropic batch distillation was used to separate this azeotrope 4 using different entrainers including water, acetonitrile, nitromethane, and methanol. 5 This technique is characterized by some setbacks which include long exposure times of the mixture to high temperatures that can result in thermal degradation.…”

Design and Control of a Middle Vessel Batch Distillation Process for Separating the Methyl Formate/Methanol/Water Ternary System

“…Batch distillation is widely used in fine chemical production such as in the pharmaceutical industry. − Diwekar divided batch distillation processes into six types, one of which is called batch distillation with a middle vessel. The middle vessel batch distillation process has attracted much scholarly attention in recent years. − Barolo et al found that the feed rate to the column affects the column performance, and operation at infinite reflux and reboil ratios may be more profitable.…”

Choice of suitable entrainer in heteroazeotropic batch distillation system for acetic acid dehydration

“…Two simple entrainer selection rules are proposed, which make it possible to screen entrainers for heterogeneous azeotropic batch distillation with minimum efforts. Systematic study of the separation of the n-hexane-ethyl acetate mixture and another paper for the separation of tert-butyl alcohol-water mixture with an entrainer by heterogeneous azeotropic batch distillation were performed in Rodriguez-Donis et al (2005) and in Xu and Wand (2006), respectively. A general method for the calculation of residue curves and for the determination of batch distillation regions of heteroazeotropic distillation was suggested in Lang and Modla (2006).…”