Research ArticleChemistry

Paralyzed membrane: Current-driven synthesis of a metal-organic framework with sharpened propene/propane separation

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Science Advances  26 Oct 2018:
Vol. 4, no. 10, eaau1393
DOI: 10.1126/sciadv.aau1393

Abstract

Metal-organic framework (MOF) membranes show great promise for propene/propane separation, yet a sharp molecular sieving has not been achieved due to their inherent linker mobility. Here, zeolitic imidazolate framework ZIF-8–type membranes with suppressed linker mobility are prepared by a fast current–driven synthesis (FCDS) strategy within 20 min, showing sharpened molecular sieving for propene/propane separation with a separation factor above 300. During membrane synthesis, the direct current promotes the metal ions and ligands to assemble into inborn-distorted and stiffer frameworks with ZIF-8_Cm (a newly discovered polymorph of ZIF-8) accounting for 60 to 70% of the membrane composition. Molecular dynamics simulations further verify that ZIF-8_Cm is superior to ZIF-8_I Embedded Image (the common cubic phase) for propene/propane separation. FCDS holds great potential to produce high-quality, ultrathin MOF membranes on a large scale.

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