T-type capture site within highly stable bicarbazole-based metal–organic framework for C2H2 purification from CO2 and CH4

It is challenging to achieve high-purity acetylene (C2H2) from the methylene (CH4) and carbon dioxide (CO2), due to their similar molecular structure and physical properties. Adsorption utilized porous materials, such as metal–organic frameworks (MOFs), has been considered as cost- and energy-efficient technology to separate acetylene mixtures. Herein, we reported a highly stable MOF, [Zn6L4(Me2NH2+)4‧3H2O] (named FJU-83), featuring T-shaped functional capture sites explored for acetylene capture and separation. In addition, FJU-83a exhibits not only a high C2H2 uptake capacity of 122.9 cm3/g at 273 K, 1 bar, but also good C2H2/CH4 and C2H2/CO2 selectivity of 24 and 2.9 under moderate temperature and 1 bar, respectively. The high separation efficiency of the C2H2/CH4 and C2H2/CO2 are validated by dynamic fixed bed breakthrough experiments. The single crystal X-ray diffraction studies and Hirshfeld surface analysis revealed that T-type aromatic sites of FJU-83a can separate C2H2 from CH4 and CO2 through multiple C-H∙∙∙π and π∙∙∙π interactions.