Efficient separation of ethylene from acetylene/ethylene mixtures by a flexible-robust metal–organic framework

During the production of polymer-grade ethylene, trace amounts of acetylene (about 1%) in the ethylene feed need to be reduced to 40 parts per million (ppm). We herein report a metal–organic framework (MOF) of flexible-robust nature for the efficient removal of acetylene from acetylene/ethylene mixture to meet such a challenging separation need. Neutron powder diffraction studies reveal that its specific binding sites and unique pore structure collectively enable this MOF (ELM-12) to efficiently and selectively adsorb acetylene over ethylene under ambient conditions, making it feasible for this challenging separation. The purity of obtained ethylene is over 99.999%, as demonstrated by experimental breakthrough curves of 1/99 acetylene/ethylene mixture.