(152bd) Mixed Matrix Membranes for Separating Hydrofluorocarbon Refrigerant Mixtures

Refrigerants are used daily in transportation, cooling, and manufacturing. However, due to the high global warming potential of hydrofluorocarbons (HFC) refrigerants, legislation such as the American Innovation and Manufacturing (AIM) Act will require many HFCs and HFC mixtures to be phased down over the next two decades. Currently, if a refrigerant is not recycled, it is often vented or incinerated which damages the environment. However, recycling is challenging because many refrigerant mixtures are azeotropic, which prevents separation using standard techniques such as fractional distillation. One potential method to address this challenge is the combination of an ionic liquid (IL) with a polymer to create a Mixed Matrix Membrane (MMM).

The goal of this project was to separate the commonly used refrigerant R-410A, which is a blend of 50 wt% difluoromethane (HFC-32, CH₂F₂) and 50 wt% pentafluoroethane (HFC-125, CHF₂CF₃). ILs contain unique physical properties that make them ideal for working with refrigerants. The IL can be tuned to have high selectivity for one refrigerant versus the other by controlling solubility and diffusivity with various cation and anion combinations. This study reveals promising potential of a polyvinyl acetate (PVAc) membrane and three various ILs 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]). The poster will discuss how varying anions and fluorination of the IL affects selectivity as well as details about the method for fabricating a successful MMM.