(428b) Composite Hollow Fiber Membranes with a Selective Layer of an Amorphous Perfluoropolymer for the Separation of R-410A

The separation of hydrofluorocarbon (HFC) refrigerant mixtures is a pressing issue due to environmental legislation regulating their use and production and requiring reclaimed refrigerant to be used in new applications. There is currently no technology deployed in the refrigerant industry for separating azeotropic refrigerant mixtures and energy efficient solutions are needed to avoid wasted refrigerant value and mitigate environmental consequences. Perfluoropolymers have been explored in the literature for HFC separation with small-scale membrane films, but industrial scale applications require larger surface area to volume for efficient and cost-effective separations. Composite hollow fiber membranes of polypropylene coated with a selective layer of perfluoro(butenyl vinyl ether) (PBVE) and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD) were developed with a continuous reel-to-reel coating apparatus. Correlations for coating thickness as a function of polymer concentration and velocity were developed using Landua’s law. SEM imaging was used to verify coating thickness and uniformity. The coated fibers were assembled into membrane modules and permeability and selectivity were measured for the separation of R-410A, a 50-50 wt% mixture of difluoromethane (HFC-32, CH₂F₂) and pentafluoroethane (HFC-125, CHF₂CF₃). Preliminary results indicate that a high purity of HFC-32 (> 95 mol%) can be achieved in a single pass. Future work is focused on simulating multi-stage separation and process-simulation modeling in ASPEN using the MEMSIC software package.