(715a) Linker Doping As an Effective Strategies to Tune in-Situ Formed Zeolitic-Imidazolate Framework-8 Fillers in Mixed-Matrix Membranes for Propylene/Propane Separation

Zeolitic-imidazole framework-8 (ZIF-8) has been extensively studied as a molecular sieving filler in mixed-matrix membranes (MMMs) for propylene/propane separation. The propylene/propane separation performance of ZIF-8-containing MMMs has yet to meet the commercial viability criteria. Doping or mixing linkers in ZIF-8 framework has been found effective in tuning the molecular sieving properties of ZIF-8. Recently, these doping/mixing strategies have been successfully applied to polycrystalline ZIF membranes. However, there have been no reports on applying the same strategies in tuning the molecular sieving properties of ZIF fillers in MMMs. In this presentation, we plan to present tuning of the molecular sieving properties of ZIF-8 fillers in MMMs by doping with 2-ethylimidazole (eIm) linkers in order to improve their propylene/propane separation performance. MMMs were prepared by in-situ forming eIm-doped ZIF-8 fillers in polyimide using our recently reported polymer-modification-enabled in-situ MOF formation (PMMOF) process. As eIm linkers were doped into ZIF-8 filler crystals, the propylene/propane separation factor of the resulting MMMs was dramatically enhanced. Lastly, doped-linker ZIF-8 based mixed-matrix hollow fiber membranes were successfully prepared, demonstrating potential of their scalable practical applications.