(400c) Screening Ionic Liquids for Refrigerant Separation Using Gas Chromatography

The separation of refrigerant mixtures is a critical challenge in refrigerant recovery and reuse, particularly as regulations on high-global-warming-potential (GWP) refrigerants become stricter. Ionic liquids (ILs) have emerged as promising separation agents due to their negligible vapor pressures, adjustable solvation properties, and high thermal stability. However, selecting an optimal IL for a given refrigerant mixture remains a challenge due to the wide number of possible IL structures. In this study, we propose a novel screening method utilizing gas chromatography (GC) to evaluate ILs for refrigerant separation. By coating a capillary column with a thin film of IL and injecting various refrigerants, we can analyze retention times to assess interactions between the IL and each refrigerant. Given their dual-nature behavior—acting as both polar and nonpolar stationary phases—ILs can be tailored for selective separations, even at elevated temperatures comparable to commercial gas-liquid chromatography (GLC) phases. This approach provides a high-throughput, reproducible method for identifying ILs best suited for selective refrigerant separations, with implications for sustainable refrigerant management.