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

Rational design and engineering of high-performance molecular sieve membranes towards C H /C H 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@NH -MIL-125 membrane was successfully prepared. Coordinatively unsaturated Cu ions immobilized in the NH -MIL-125 framework enabled high-affinity π-complexation interactions with C H , resulting in an C H /C H selectivity approaching 13.6, which was 9.4 times higher than that of pristine NH -MIL-125 membrane; moreover, benefiting from π-complexation interactions between CO and Cu(I) sites, our membrane displayed superior CO /N selectivity of 43.2 with CO 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.