(152av) Separation of HFC-32 and HFC-125 Using Polyvinyl Acetate + Ionic Liquid Composite Membranes

Hydrofluorocarbons (HFCs) are greenhouse gases commonly used in refrigeration systems. Current legislation has called for the phase-out of HFCs due to many of them containing a high global warming potential. Since many refrigerants are found as HFC mixtures, methods for separating and recycling these compounds are crucial. In the past, ionic liquids and polymers have been used separately for this application. The incorporation of ionic liquid into polymer membranes creates a great possibility for more efficient separations due to both entities having separation potential. The ability to create a composite membrane harnessing the characteristics of both the polymer and the ionic liquid is attractive for the separation of refrigerants. In this work, the permeability and selectivity of difluoromethane (HFC-32) and pentafluoroethane (HFC-125) are investigated in ionic liquid polymer membranes of polyvinyl acetate (PVAc) with three ionic liquids, 1-hexyl-3-methylimidazolium ([C₆C₁im][Cl]), 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₆C₁im][Tf₂N]), and 1-hexyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate ([C₆C₁im][FAP]) with various weight percents. The membranes were evaluated for their glass transition temperature to investigate the effect of increasing ionic liquid concentration. Results of this study indicate that incorporating ionic liquids into polymer membranes can create solubility tunability for the separation of hydrofluorocarbons.