Ionic Liquid Stabilizes Olefin Facilitated Transport Membranes Against Reduction

Separation of olefins from their paraffin analogs relies on energy-intensive cryogenic distillation. Facilitated transport-based membranes that reversibly and selectively bind olefins, but not paraffins, could save considerable amounts of energy. However, the chemical instability of the silver ion olefin-binding carriers in such membranes has been a longstanding roadblock for this approach. We discovered long-term carrier stability against extended exposure to hydrogen, a common contaminant in such streams. Based on UV/Vis absorption and Raman spectroscopy, along with XRD analysis results, certain ionic liquids solubilize silver ions, and anion aggregates surrounding the silver ion carriers greatly attenuate their reduction by hydrogen. Here, we report the stability of olefin/paraffin separation properties under continuous exposure to high pressure hydrogen, which addresses a critical technical roadblock in membrane-based olefin/paraffin separation.