Efficient Trapping of Trace Acetylene from Ethylene in an Ultramicroporous Metal–Organic Framework: Synergistic Effect of High‐Density Open Metal and Electronegative Sites

Abstract Acetylene (C2H2) removal from ethylene (C2H4) is a crucial step in the production of polymer‐grade C2H4but remains a daunting challenge because of the similar physicochemical properties of C2H2and C2H4. Currently energy‐intensive cryogenic distillation processes are used to separate the two gases industrially. A robust ultramicroporous metal–organic framework (MOF), Ni3(pzdc)2(7 Hade)2, is reported for efficient C2H2/C2H4separation. The MOF comprises hydrogen‐bonded linked one‐dimensional (1D) chains, and features high‐density open metal sites (2.7 nm−3) and electronegative oxygen and nitrogen sites arranged on the pore surface as cooperative binding sites. Theoretical calculations, in situ powder X‐ray diffraction and Fourier‐transform infrared spectroscopy revealed a synergistic adsorption mechanism. The MOF possesses S‐shaped 1D pore channels that efficiently trap trace C2H2at 0.01 bar with a high C2H2uptake of 60.6 cm3 cm−3and C2H2/C2H4selectivity.