MOF-derived nanocomposites functionalized carbon molecular sieve membrane for enhanced ethylene/ethane separation

Fine tailoring the pore structure and sorption capability of carbon molecular sieve (CMS) membrane is highly desirable for efficient separation of C2H4/C2H6 gas pair. In this work, a facile approach was proposed to enrich the ultramicroporosity of CMS membrane and enhance the affinity adsorption capacity for C2H4, in which ZIF-8 nanoparticles were incorporated into a novel precursor polymer of phenolphthalein-based poly (arylene ether ketone) (PEK-C) followed by carbonization to prepare mixed matrix CMS membranes to achieve simultaneously high C2H4 permeability and high C2H4/C2H6 selectivity. The ZIF-8-derived nanocomposites partially maintain the pore structure of ZIF-8 precursor, and have good compatibility with the carbon matrix. The BET surface areas, micropore volume and the number of ultramicropore with molecular sieving ability of CMS membrane are greatly improved due to the introduction of ZIF-8-derived microporous carbons, resulting in a significant increase in the C2H4 permeability and C2H4/C2H6 diffusion selectivity. The C2H4/C2H6 sorption selectivity of CMS membrane is also enhanced owing to the selective adsorption affinity of the ZIF-8-derived Zn2+ metal oxides for C2H4. The C2H4 permeability of mixed matrix CMS membrane with 10 wt% ZIF-8 loading is increased by 42% compared to that of neat CMS membrane, and the C2H4/C2H6 selectivity is increased by 102%.