Thermodynamic Modeling of the Phase Behavior of Binary Systems of Ionic Liquids and Carbon Dioxide with the Group Contribution Equation of State

Abstract

The group contribution equation of state (GC-EOS) was applied to predict the phase behavior of binary systems of ionic liquids of the homologous families 1-alkyl-3-methylimidazolium hexafluorophosphate and tetrafluoroborate with CO2. Pure group parameters for the new ionic liquid functional groups [-mim][PF6] and [-mim][BF4] and interaction parameters between these groups and the paraffin (CH3, CH2) and CO2 groups were estimated. The GC-EOS extended with the new parameters was applied to predict high-pressure phase equilibria in binary mixtures of the ionic liquids [emim][PF6], [bmim][PF6], [hmim][PF6], [bmim][BF4], [hmim][BF4], and [omim][BF4] with CO2. The agreement between experimental and predicted bubble point data for the ionic liquids was excellent for pressures up to 20 MPa, and even for pressures up to about 100 MPa, the agreement was good. The results show the capability of the GC-EOS to describe phase equilibria of systems consisting of ionic liquids.

Modeling ionic liquids and the solubility of gases in them: Recent advances and perspectives

“…Image of the molecule and COSMO-RS model taken from reference [186]. Sketch of GC-EoS taken from reference [144]. experimental data was used to obtain their values.…”

Thermodynamic modeling of CO2 solubility in ionic liquid with heterosegmented statistical associating fluid theory

“…In the models of hetero-nuclear square-well chain fluids [28], group-contribution non-random lattice fluid equation of state [29], and group-contribution equation of state [30], the imidazolium ring-anion pair was modeled as one segment or functional group. As can be concluded from those works, all of these models utilize model parameters that are not completely transferable.…”

Prediction of molar volume and partial molar volume for CO2/ionic liquid systems with heterosegmented statistical associating fluid theory

“…Recently, SAFT EOS has been extended to describe the gas solubility in ILs [33] where an IL molecule was modelled as a neutral ion pair with one set of parameters or a combination of cation and anion [34]. In the models of hetero-nuclear square-well chain fluids [35] and group contribution equation of state [36], the imidazolium ringanion pair was modelled as one segment or functional group. As can be concluded, all of these models utilize model parameters that are not completely transferable.…”