Effect of cation on the solubility of ethane in three bis(fluorosulfonyl) imide ([FSI]) based low viscosity ionic liquids

The solubility of ethane (C2H6) in three ionic liquids (ILs) with the same anion, [C(3)C(1)pip][FSI], [C(3)C(1)pyrr] [FSI] and [N-1223][FSI], was measured at (303.15, 323.15, and 343.15) IC and at pressures up to 1.1 MPa. Experimental data were correlated with Peng-Robinson (PR) equation of state using three different mixing, rules: (i) van der Waals one (vdW1, based on a single binary interaction parameter), (ii) van der Waals two (vdW2, based on two binary interaction parameters), and (iii) Wong-Sandler mixing rules combined with NRTL model. Henry's law constants, enthalpy and entropy for the absorption of ethane in these ILs were also estimated. No significant change was found in the values of Henry's law constants of C2H6 in these three ILs which indicates a negligible effect of cations of these ILs on C2H6 solubility. The selectivity towards carbon dioxide (CO2) over C2H6 for these ILs was also reported. [FSI]-based ILs seem to have higher selectivity than all the other Its, except for [C(4)C(1)Im] [BF4] and possibly [C(4)C(1)Im][PF6], which may qualify them as promising solvents for CO2 removal from natural gas streams. (C) 2017 Elsevier B.V. All rights reserved.