(653f) Liquid-Liquid Equilibria of Ternary Systems of Thermally Robust Ionic Liquids and Hydrocarbon Mixtures

Hydrocarbon (HC) separations is an energy intensive process due to similar boiling points and formation of azeotropes. Here, we test different novel thermally robust perarylphosphonium and perarylsulfonium ionic liquids (ILs) for separating aromatic compounds from HC mixtures. Molecular dynamics (MD) simulations are used to provide a molecular-level understanding of these systems. Simulations of binary mixtures of toluene/ILs and n-heptane/ILs are performed to validate and study the miscibility behavior. Ternary mixtures consisting of IL/toluene/n-heptane at different concentrations of toluene in n-heptane are carried out to determine the amount of toluene absorbed into IL phase. Further, the fundamental interactions between aromatics and IL leading to this behavior are assessed through radial distribution functions and nearest neighbor analysis. Selectivity and distribution coefficients are determined to evaluate the affinity of toluene between IL and HC phase. The free energy of solvation (∆G_solvation) and transfer free energy (∆G_transfer) of toluene in different solvents are calculated using thermodynamic integration (TI) method. The results show that ∆G_solvation of toluene is more favorable in all the ILs compared to n-heptane. Overall the simulation results provide a molecular-level understanding of the solvent environment provided by these ILs in separating aromatics from hydrocarbon mixtures.