Ionic liquids as separating agents in extractive rectification

• The regularities of extractive rectification with ionic liquids were studied.
• Separating agent selectivity was estimated.
• Ionic liquids were proved as efficient extractive agents by natural experiment.

This article presents extractive rectification of binary mixtures. The choice of extractive agents was made from a set of well-known separating agents with ionic liquids. Gas–liquid chromatography was used to estimate the separating agent selectivity. Vapour–liquid equilibrium mathematical modelling was used to predict the quality of the product. The applicability of ionic liquids in extractive rectification of different binary azeotropic mixtures (both positive and negative azeotropes) was proved by laboratory experiments and computer simulations. Experimental conditions, parameters of rectification column and the separation results are presented.