Fluorinated Polyimide Materials and Membranes in Olefin/Paraffin Separation

Fluorinated polyimide (FPI) polymers offer an excellent combinations of high fractional free volume (FFV), outstanding thermal stability, and chemical resistance properties that are critical for molecular separations. In addition, FPIs provide distinct advantages for the fabrication of mixed-matrix membranes and carbon molecular sieve membranes due to their robust mechanical properties, and ease of chemical modification that enhance filler compatibility and enable efficient carbonization. This review summarizes recent studies on the use of FPI-derived membrane materials for the highly energy-intensive olefin/paraffin separation process. It begins by discussing various glassy polymers particularly FPI polymers, used as precursors for membrane formation. The review then examines different fluorinated and nonfluorinated copolyimides membrane materials and fabrication methods aimed at overcoming current limitations related to stability and the permeability-selectivity trade-off. Subsequently, it highlights the most effective membrane materials and operating conditions reported for olefin/paraffin separation. The review also discusses how FPI membranes address key challenges such as plasticization, physical aging, and the inherent trade-off between permeability and selectivity factors critical for long-term industrial applications. Finally, the review concludes with perspectives on future research directions and industrial translation of FPI-based membranes, drawing on insights from the peer-reviewed literature.