Absorption Separation\nof Binary Refrigerant Blends\nUsing 1‑Butyl-3-methylimidazolium Thiocyanate Ionic Liquid

Extractive distillation using ionic liquids (ILs) as\nan entrainer\nis a promising way to separate azeotropic or near-azeotropic refrigerant\nmixtures. The vapor–liquid phase equilibrium between the refrigerant\nand ILs is one of the essential properties to evaluate the separation\nperformance. In this work, the solubility of difluoromethane (R32),\npentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 2,3,3,3-tetrafluoroprop-1-ene\n(R1234yf), and <i>trans</i>-1,3,3,3-tetrafluoropropene (R1234ze(E))\nin 1-butyl-3-methylimidazolium thiocyanate ([C<sub>4</sub>mim][SCN])\nionic liquid was investigated. The isochoric saturation method was\nused for the solubility measurement, and the studied temperature range\nwas from 283.15 to 323.15 K. In addition, the ideal selectivity at\ninfinite dilution of [C<sub>4</sub>mim][SCN] for four refrigerant\nmixtures including R32/R125, R32/R1234yf, R134a/R1234yf, and R134a/R1234ze(E)\nwas calculated and analyzed. Results show that [C<sub>4</sub>mim][SCN]\ncan be considered as a potential entrainer for separation of R32/R125,\nR32/R1234yf and R134a/R1234yf mixtures.