COSMO-based/Aspen Plus process simulation of the aromatic extraction from pyrolysis gasoline using the {[4empy][NTf2] + [emim][DCA]} ionic liquid mixture

Abstract

The ionic liquids (ILs) has been widely studied as potential replacements of conventional solvents in the extraction of aromatic hydrocarbons from alkanes. However, the majority of the papers have been focused in obtaining experimental data of liquid-liquid equilibria without studying whole process of extraction and separation of the extracted hydrocarbons from the solvent. In this paper, a computer-aided methodology combining molecular simulation by COSMO-based methodology and process simulation by Aspen Plus has been employed to study the extraction process of aromatic hydrocarbons from pyrolysis gasoline employing a binary mixture of 1-ethyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4empy][NTf2]) and the 1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]) ILs as solvent. A comparison between experimental data and the predictions obtained by the COSMO-based thermodynamic model of liquid-liquid and vapor-liquid equilibria and physical properties of the ILs was made for validation purpose. Process simulations were performed employing three configurations with one, two, or three flash distillations in the recovery section and the IL mixture over the whole range of composition as solvent. The configuration with three flash distillations and the binary IL mixture with a 75 % of [4empy][NTf2] were selected as the optimal conditions to increase aromatic recovery and purity.