Modeling the phase behavior of ternary systems ionic liquid + organic + CO 2 with a Group Contribution Equation of State

This work presents the results of the use of a Group Contribution Equation of State (GC‐EOS) to model experimental data obtained for ternary systems of the type bmim[BF 4 ] + organic solute + CO 2 with four different organic compounds, namely acetophenone, 1‐phenylethanol, 4‐isobutylacetophenone, and 1‐(4‐isobutylphenyl)‐ethanol. Our results show that the GC‐EOS is able to qualitatively predict not only L+V→L but also L 1 +L 2 →L phase transitions. As the two two‐phase boundaries L+V and L 1 +L 2 of the experimentally found three‐phase region L 1 +L 2 +V almost coincide with the saturated vapor pressure curve of pure CO 2 , the phase transitions L+V→L 1 +L 2 +V and L 1 +L 2 +V→L 1 +L 2 have been represented as this vapor‐pressure curve by the model. The average absolute deviations between experimental and predicted values for all phase transitions have been found to be very satisfactory. © 2009 American Institute of Chemical Engineers AIChE J, 2009