Oriented Ultrathin π‐complexation MOF Membrane for Ethylene/Ethane and Flue Gas Separations

Rational design and engineering of high-performance molecular sieve membranes towards C2 H4 /C2 H6 and flue gas separations remain a grand challenge to date. In this study, through combining pore micro-environment engineering with meso-structure manipulation, highly c-oriented sub-100 nm-thick Cu@NH2 -MIL-125 membrane was successfully prepared. Coordinatively unsaturated Cu ions immobilized in the NH2 -MIL-125 framework enabled high-affinity π-complexation interactions with C2 H4 , resulting in an C2 H4 /C2 H6 selectivity approaching 13.6, which was 9.4 times higher than that of pristine NH2 -MIL-125 membrane; moreover, benefiting from π-complexation interactions between CO2 and Cu(I) sites, our membrane displayed superior CO2 /N2 selectivity of 43.2 with CO2 permeance of 696 GPU, which far surpassed the benchmark of other pure MOF membranes. The above multi-scale structure optimization strategy is anticipated to present opportunities for significantly enhancing the separation performance of diverse molecular sieve membranes.