(629c) Polyimide Membranes for Sustainable Refrigerant Recovery: Hydrocarbon-HFC Separation

Refrigeration is a very large and integral part of modern day life, but refrigerant use has a significant environmental impact. Hydrofluorocarbons (HFCs) have high global warming potentials and recent legislations are seeking to regulate and phase out HFC refrigerants by 2035. The increasing demand for efficient and sustainable refrigerant recovery has driven research into energy-efficient separation technologies. Contamination of refrigerant gases with hydrocarbon mixtures complicates recycling efforts. Membrane separation technology presents a low-energy alternative for removing hydrocarbons from refrigerant mixtures, facilitating cleaner refrigerant recovery. This research focuses on the use of Matrimid® 5218, an aromatic polyimide polymer, membranes for the removal of hydrocarbons from HFCs. The membranes were synthesized using N-methyl-2-pyrrolidinone (NMP) solvent, followed by controlled drying in a vacuum oven at 100°C and annealing at 150°C for over 24 hours to enhance separation performance. Permeability measurements were conducted at 25°C and 2 bar for propane, isobutane, difluoroethane (HFC-32), and pentafluoroethane (HFC-125).