(606g) Separation of Fluorocarbon Refrigerants Using Copolymer Membranes of Perfluoro(2,2-dimethyl-1,3-dioxole) (PDD) and Vinyl Acetate (VA)

Refrigeration is a vital part of modern life; however, the use of refrigerants has an environmental impact. Recent legislation such as the 2020 American Innovation and Manufacturing (AIM) Act seeks to regulate and phase-down hydrofluorocarbon (HFC) refrigerants by 80% by 2035. With the current legislative focus on the regulations of HFCs, sustainable methods for separating and recycling refrigerants are needed. Membrane separation provides the potential to separate refrigerants using energy-efficient technology. This research focuses on copolymers of perfluoro(2,2-dimethyl-1,3-dioxole) (PDD) and vinyl acetate (VA) to be used as a membrane material for separation of common refrigerants such as HFCs, hydrochlorofluorocarbons (HCFCs), and hydrofluoroolefins (HFOs). The permeability of difluoromethane (HFC-32, CH₂F₂), pentafluoroethane (HFC-125, CHF₂CF₃), 1,1,1,2-tetrafluoroethane (HFC-134a, C₂H₂F₄), chlorodifluoromethane (HCFC-22, CHClF₂) and 2,3,3,3-tetrafluoropropene (HFO-1234yf, C₃H₂F₄) were measured in a copolymer of 25 % vinyl acetate (VA) and 75% perfluoro(2,2-dimethyl-1,3-dioxole) (PDD) at 35 °C and 2 bar. Solubility and diffusivity for each gas in this copolymer were also measured using a gravimetric microbalance. Results indicate that PDD-VA is a promising copolymer for the separation of HFC-32 from mixtures containing HFC-125, HFC-134a, and HFO-1234yf, with an HFC-32 permeability of approximately 340 Barrer and selectivities as high as 10 for certain gas pairs.