Dynamic molecular pockets on one-dimensional channels for splitting ethylene from C 2 –C 4 alkynes

Molecular sieving adsorbents can offer maximum adsorption selectivity with respect to molecular sizes, yet it is still challenging to discriminate middle-sized molecules from a mixture of three or more components. Here we report a metal–organic framework (JNU-3a) with dynamic molecular pockets along one-dimensional channels, enabling the one-step removal of ethylene (C 2 H 4 ) from mixtures with C 2 –C 4 alkynes in a single adsorption step regardless of their molecular sizes. Laboratory-scale column breakthrough experiments on 1.4 g of JNU-3a reveal that the three alkynes break through the column at almost the same but a later time, resulting in the high-purity separation of C 2 H 4 (≥99.9995%) from a mixture with C 2 –C 4 alkynes in a single adsorption operation. We further demonstrate pilot-scale column breakthrough on 107 g of JNU-3a and the collection of C 2 H 4 in a gas cylinder. In particular, 30 continuous runs for a C 2 H 2 /C 3 H 4 /1-C 4 H 6 /C 2 H 4 mixture (1:1:1:97) afford an average of 76.1 g per cycle of high-purity C 2 H 4 . Overall, JNU-3a may have great potential for industrial C 2 H 4 purification via the concurrent removal of C 2 –C 4 alkynes.