Pore environment modulation of metal-organic frameworks enables efficient adsorptive separation of Xe/Kr

Abstract

Efficient adsorptive separation of xenon/krypton (Xe/Kr) mixtures is industrially significant, but design of adsorbents coalescing high adsorption capacity and selectivity remain an unmet challenge. Herein, we introduce the fine tailoring of pore environments in isomorphic metal–organic framework variants by changing aromatic ring number of ligands. As increase of aromatic rings, stronger Xe-host is elicited relying upon the optimized pore aperture and favourable channel microenvironment. As a result, Ni(NDC)(TED)0.5 displays an ultra-high Xe uptake of 5.56 mmol g−1 and considerable Xe/Kr selectivity of 12.9, affording a new benchmark adsorbent for Xe/Kr adsorptive separation. Further pore downsizing leads to a higher selectivity (24.7) but a decreased Xe uptake (3.25 mmol g−1) on Ni(ADC)(TED)0.5. Computational calculations reveal that abundant C–H groups and suitable pore size are responsible for the efficient Xe separation. Dynamic breakthrough experiments further validate excellent Xe/Kr separation performances on Ni(NDC)(TED)0.5.