One-step ethylene production from a four-component gas mixture by a single physisorbent

One-step adsorptive purification of ethylene (C 2 H 4 ) from four-component gas mixtures comprising acetylene (C 2 H 2 ), ethylene (C 2 H 4 ), ethane (C 2 H 6 ) and carbon dioxide (CO 2 ) is an unmet challenge in the area of commodity purification. Herein, we report that the ultramicroporous sorbent Zn-atz-oba (H 2 oba = 4,4-dicarboxyl diphenyl ether; Hatz = 3-amino-1,2,4-triazole) enables selective adsorption of C 2 H 2 , C 2 H 6 and CO 2 over C 2 H 4 thanks to the binding sites that lie in its undulating pores. Molecular simulations provide insight into the binding sites in Zn-atz-oba that are responsible for coadsorption of C 2 H 2 , C 2 H 6 and CO 2 over C 2 H 4 . Dynamic breakthrough experiments demonstrate that the selective binding exhibited by Zn-atz-oba can produce polymer-grade purity (>99.95%) C 2 H 4 from binary (1:1 for C 2 H 4 /C 2 H 6 ), ternary (1:1:1 for C 2 H 2 /C 2 H 4 /C 2 H 6 ) and quaternary (1:1:1:1 for C 2 H 2 /C 2 H 4 /C 2 H 6 /CO 2 ) gas mixtures in a single step. The purification of ethylene is an industrially relevant process. Here, the authors report the one-step separation of ethylene from quaternary gas mixtures of hydrocarbons and CO 2 using a single metal–organic framework-based physisorbent.