Organic Cage with Interconnected Aromatic Cavity‐Channel Pores for One‐Step Purification of Ethylene
Junning Kou, Dongxu Cui, Jianzhu Jiang, Wenliang Li, Guo‐Gang Shan, Hao Wang, Xinlong Wang, Zhongmin Su, Chunyi Sun
Abstract
Abstract Constructing a metal‐free adsorbent for one‐step separation of C 2 H 4 from mixture gas of C2, is of great significance and challenging. Here, a porous aromatic cage ( PAC‐1 ) based on aldehyde‐amine condensation is reported with diamond‐like interconnected aromatic cavity‐channel pores for one‐step purification of ethylene. PAC‐1 exhibits superior C 2 H 2 (52.6 cm 3 g −1 ) and C 2 H 6 (46.7 cm 3 g −1 ) uptakes as well as impressive C 2 H 2 /C 2 H 4 selectivity (1.5) and C 2 H 6 /C 2 H 4 selectivity (1.4), remaining at the forefront of the advanced C 2 H 4 ‐selective adsorbents of porous non‐metallic materials. The C 2 H 4 adsorption enthalpy (Q st ) of PAC‐1 is of 23.6 kJ mol −1 , which requires less energy to regenerate than conventional MOF materials. Breakthrough experiments demonstrate that PAC‐1 can reduce the penetration rate of C 2 H 6 or C 2 H 2 through the adsorbent, and present quite valuable one‐step separation of C 2 H 4 from C 2 H 2 /C 2 H 6 /C 2 H 4 mixture gas. Molecular simulations and DFT studies have shown that oxygen sites and C─H sites in the channels are more favorable for C 2 H 2 anchor with interaction energy over C 2 H 4 by 1.48 kcal mol −1 , and the C─H…π interaction point in cage cavity is preferred to C 2 H 6 with the interaction energy over C 2 H 4 by 1.16 kcal mol −1 , which in turn results in the separation of C 2 H 4 from C 2 H 2 and C 2 H 6 .