Commensurate stacking within confined ultramicropores boosting acetylene storage capacity and separation efficiency

Abstract

Developing advanced porous materials possessing both a high storage capacity and selectivity for acetylene (C2H2) remains challenging but a sought-after endeavor. Herein we show a strategy involving synergic combination of spatial confinement and commensurate stacking for enhanced C2H2 storage and capture via maximizing the host—guest and guest—guest interactions. Two ultramicroporous metal-organic frameworks (MOFs), MIL-160 and MOF-303 are elaborately constructed to exhibit ultrahigh C2H2 uptakes of 235 and 195 cm3·g−1, respectively, due to the confinement effect of the suitable pore sizes and periodically dispersed molecular recognition sites. Specially, C2H2 capacity of MIL-160 sets a new benchmark for C2H2 storage. The exceptional separation performances of two materials for C2H2 over both CO2 and ethylene (C2H4), which is rarely observed, outperform most of the benchmark materials for C2H2 capture. We scrutinized the origins of ultrahigh C2H2 loading in the confined channels via theoretical investigations. The superior separation efficiency for C2H2/CO2 and C2H2/C2H4 mixtures with unprecedented C2H2 trapping capacity (> 200 L·kg−1) was further demonstrated by dynamic breakthrough experiments.