One of the most pressing environmental concerns facing humanity today is the limitation of carbon dioxide emissions. In the field of natural gas sweetening, carbon capture is equally critical. The solubility of carbon dioxide (CO₂) and ethane (C₂H₆) in three ionic liquids (ILs) with the same anion, [C₃C₁pip][FSI], [C₃C₁pyrr] [FSI] and [N1223][FSI], was measured at (303.15, 323.15, and 343.15) K 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 Carbon dioxide and 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 ILs, except for [C₄C₁Im][BF4] and possibly [C₄C₁Im][PF6], which may qualify them as promising solvents for CO₂ removal from natural gas streams.