Organic Cage with Interconnected Aromatic Cavity‐Channel Pores for One‐Step Purification of Ethylene

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 .