Abstract: Ionic liquids (ILs) are promising entrainers for the separation of azeotropic refrigerant mixtures, particularly within the ongoing transition toward low-global-warming-potential (GWP) alternatives. The development of extractive distillation processes requires reliable vapor-liquid equilibrium (VLE) data and accurate thermodynamic models. In this work, the solubility of several hydrofluorocarbons (R-32, R-125 and R-134a), hydrof luoroolefins (R-1234yf and R-1234ze(E)) and CO2 in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([C2C1im][FSI]) was experimentally determined over temperatures from 283.15 to 323.15 K and pressures up to 1.1 MPa applying the isochoric saturation method. All refrigerant/IL systems were satisfactorily described using both the Peng-Robinson equation of state coupled with the Boston-Mathias mixing rule and the Non-Random Two-Liquid (NRTL) activity coefficient model, yielding average absolute deviations below 1% and 6%, respectively. The relative absorption performance was assessed through the Henry´s law constants and mixing thermodynamic properties, showing that the IL selected exhibited high ideal selectivity towards different refrigerant blends. In the case of R-410A, a near-azeotropic mixture of R-32 and R-125, the [C2 C1 im][FSI] selectivity was higher than previously reported for any other IL with a fluorinated anion, yet lower than for nitrile-based ILs. Furthermore, an upper-bound relationship between the ideal R-32/R-125 selectivity and R-32 absorption capacity was reported for the first time, establishing a quantitative benchmark for future IL screening and design. The presented data and its subsequent analysis expand the available thermodynamic knowledge for refrigerant/ IL systems and provide a basis for future development an IL-based separation process for R-410A.
