Evaluation of ionic liquids as solvent for aromatic extraction: Experimental, correlation and COSMO-RS predictions

For the study of the separation of benzene or toluene from octane, nonane and cyclooctane, the ionic liquids 1-butyl-3-methylimidazolium methylsulfate, BMimMSO4, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, BMimNTf2, were used as solvents. The (liquid + liquid) equilibria of the ternary systems {octane, or nonane, or (cyclooctane + benzene + BMimMSO4)}, and {(nonane + toluene + BMimMSO4) or BMimNTf2} at T = 298.15 K were determined, and an analysis of the influence of the structure of each compound was carried out. Besides, the experimental data have been compared with literature data with sulfolane as solvent. The experimental results obtained have been correlated using NRTL and UNIQUAC models. Finally, COSMO-RS has been used to predict the (liquid + liquid) equilibrium of the systems studied. The differences between the predicted and experimental values were used to evaluate the ability of the COSMO-RS model to describe the impact of the structure of the alkane, aromatic and ionic liquid on the (liquid + liquid) equilibria.

• BMimMSO4 and BMimNTf2 were studied as solvents to extract aromatic from aliphatic hydrocarbons.
• Liquid + liquid equilibrium data were measured at 298.15 K and atmospheric pressure.
• Selectivity and solute distribution ratio were obtained and compared with literature.
• Experimental data were satisfactorily correlated using NRTL and UNIQUAC models.
• COSMO-RS model was used as a predictive tool to describe the experimental LLE data for the studied ternary systems.