One Ni-MOF with gate-opening behavior for unprecedented separation of C2H2 from C2 hydrocarbons

The separation and production of highly pure C2H2 from C2H4 and C2H6 is an important task in petrochemical industry, but it is challenging to synthesize target porous materials with excellent separation properties. In this paper, we reported the construction of a novel Ni-MOF material [Ni3(F-tzba)2(bpy)3(F)2] (F-H2tzba = 2-F-4-(1H-tetrazol-5-yl) benzoic acid, bpy = 4,4′-bipyridine) by using mixed bpy and F-H2tzba coligands. Ni-MOF has a pore surface modified by carboxyl oxygen atoms, tetrazolyl nitrogen atoms and F sites to better bind to C2H2 molecules than C2H4 and C2H6. Ni-MOF displayed a unique gate-opening effect on C2H4 and C2H6 adsorption in the low-pressure region, leading to significantly high selectivity of C2H2/C2H4 and C2H2/C2H6. Breakthrough experiments proved that Ni-MOF could not only effectively separate C2H2 (≥98 % purity) from C2H2/C2H6 and C2H2/C2H4 binary mixtures but also unprecedentedly separate C2 trinary hydrocarbon mixtures to yield high-purity C2H2 (≥98 %).