Ionic Liquid Selection for the Separation of Refrigerant Mixtures Using Extractive Distillation
Ethan A. Finberg, Max Cordry, Tessie L. May, Kalin R. Baca, Mark B. Shiflett
Abstract
Separating azeotropic refrigerant mixtures is needed in the refrigerant industry to prevent the incineration or venting of end-of-life refrigerants. One promising technology for separating the refrigerant mixtures is extractive distillation with ionic liquid as the entrainer. As a continuation of previous work, two refrigerant mixtures are investigated, HFC-125/HFC-143a and HFC-32/HCFC-22, as well as R-449A (an equimass mixture of HFC-32, HFC-125, HFC-134a, and HFO-1234yf), to represent a hydrofluorocarbon/hydrofluoroolefin (HFC/HFO) system. The ionic liquids are selected based on the solubility ratio between the mixture components at elevated pressures (0.5 MPa). The ionic liquid [P (14)666 ][TMPP] is selected for separating HFC-125/HFC-143a, [C 2 C 1 im][TFES] is selected for separating HFC-32/HCFC-22, and [C 2 C 1 im][SCN] is selected for separating HFC-32/HFC-125/HFC-134a/HFO-1234yf. Aspen Plus simulations are completed for systems HFC-125/HFC-143a and HFC-32/HCFC-22, showing that these azeotropic refrigerant mixtures can be separated up to refrigerant purities of 99.5 wt % using the proper ionic liquid entrainers.