(388b) Phase Equilibria and Diffusivities of HFC-32 and HFC-125 in Encapsulated Ionic Liquids

Todays generation of refrigerants, hydrofluorocarbons (HFCs), are being phased out due to high global warming potential (GWP) by the American Innovation and Manufacturing Act. HFCs are complex refrigerant mixtures that are unable to be separated by conventional technology because majority of the mixtures form azeotropes. With 850 million kilograms of refrigerant used in cooling applications, millions of kilograms of HFC mixtures will need to utilize new technology to be efficiently recycled and repurposed at their end of life. One separation solution being investigated is the use of ionic liquids (ILs) as entrainers in extractive distillation to selectively separate azeotropic HFC mixtures. ILs show promise for the separation due to their unique properties including negligible vapor pressure, thermal and chemical stability, and solubility of many gases. Recently, IL/polymer combinations such as mixed matrix membranes, supported ILs, and encapsulated ILs (ENILs) have been investigated for a variety of applications. ENILs in particular are a new technology showing promise as a stable, re-usable, and static solution that is still able to take advantage of the IL properties while also having an increased mass transfer rate. This presentation will discuss the first solubility measurements of HFC-32 (difluoromethane, CH₂F₂) and HFC-125 (pentafluoroethane, C₂HF₅) in encapsulated ILs (ENILs) to investigate their potential as a solution for separating azeotropic refrigerant mixtures. The ENIL results are compared to solubility measurements in neat ILs. Phase equilibria data for HFC-32 and HFC-125 in both the ENILs and neat ILs were measured using a Hiden Isochema IGA gravimetric balance.