Fine tuning of molecular sieving action of aluminosilicate zeolites by organic post-functionalization for light olefin/paraffin separation

초록

Zeolite molecular sieves are widely used in gas separation and shape-selective catalysis, but these applications often require discriminating differences as little as 0.1A. Molecular sieving with such size selectivity demands zeolites with highly tunable pore diameters and adsorption properties, which are technically challenging to prepare. Nevertheless, we developed a versatile method for systematically tuning the effective size of 12-(MOR, LTL, FAU) and 10-ring (MFI) zeolite pores by covalently attaching organic molecules to zeolite frameworks via bridging oxygens using an electrophile, thereby obtaining size-selective adsorbents for light olefin/paraffin separations. 4-methoxybenzene-functionalized MOR separated ethylene from ethane with an ideal-adsorbed-solution-theory selectivity of ~5873, whereas toluene-grafted MOR completely separated propylene/propane mixtures. Therefore, tailoring the molecular sieving properties of zeolites by organic functionalization broadens their applications to challenging separations.