Efficient purification of ethene by an ethane-trapping metal-organic framework

Separating ethene (C(2)H(4)) from ethane (C(2)H(6)) is of paramount importance and difficulty. Here we show that C(2)H(4) can be efficiently purified by trapping the inert C(2)H(6) in a judiciously designed metal-organic framework. Under ambient conditions, passing a typical cracked gas mixture (15:1 C(2)H(4)/C(2)H(6)) through 1 litre of this C(2)H(6) selective adsorbent directly produces 56 litres of C(2)H(4) with 99.95%+ purity (required by the C(2)H(4) polymerization reactor) at the outlet, with a single breakthrough operation, while other C(2)H(6) selective materials can only produce ca. ⩽ litre, and conventional C(2)H(4) selective adsorbents require at least four adsorption–desorption cycles to achieve the same C(2)H(4) purity. Single-crystal X-ray diffraction and computational simulation studies showed that the exceptional C(2)H(6) selectivity arises from the proper positioning of multiple electronegative and electropositive functional groups on the ultramicroporous pore surface, which form multiple C–H···N hydrogen bonds with C(2)H(6) instead of the more polar competitor C(2)H(4).