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

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 CO2 using a single metal-organic framework-based physisorbent. One-step adsorptive purification of ethylene (C2H4) from four-component gas mixtures comprising acetylene (C2H2), ethylene (C2H4), ethane (C2H6) and carbon dioxide (CO2) 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 C2H2, C2H6 and CO2 over C2H4 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 C2H2, C2H6 and CO2 over C2H4. Dynamic breakthrough experiments demonstrate that the selective binding exhibited by Zn-atz-oba can produce polymer-grade purity (>99.95%) C2H4 from binary (1:1 for C2H4/C2H6), ternary (1:1:1 for C2H2/C2H4/C2H6) and quaternary (1:1:1:1 for C2H2/C2H4/C2H6/CO2) gas mixtures in a single step.

Automated summary

The authors developed a metal-organic framework-based physisorbent for the one-step separation of high-purity ethylene from quaternary gas mixtures, achieving polymer-grade purity in a single step. Molecular simulations provided insight into the selective adsorption mechanism of the physisorbent, Zn-atz-oba, enabling the coadsorption of acetylene, ethane, and CO2 over ethylene. Dynamic breakthrough experiments demonstrated the effectiveness of the physisorbent in producing high-purity ethylene from complex gas mixtures.