An amino-coordination metal–organic framework for highly selective C2H2/CH4 and C2H2/C2H4 separations through the appropriate control of window sizes

Abstract

The efficient separation of C₂H₂ versus C₂H₄ and CH₄ to obtain high-purity C₂H₂ and C₂H₄ is of significance for making full, economic use of these raw chemicals. Herein, an amino-coordination microporous metal–organic framework ZJU-198, ZnL·DMF (ZJU = Zhejiang University, L = (2E,2E′)-3,3′-(5-amino-1,3-phenylene)diacrylic acid, DMF = N,N′-dimethylformamide), has been demonstrated as a valuable adsorbent for C₂H₂/C₂H₄ and C₂H₂/CH₄ separations. The activated ZJU-198a exhibits moderate C₂H₂ uptakes (99.4 cm³ cm⁻³ for 273 K and 98.4 cm³ cm⁻³ for 298 K under 1.0 bar) and moderately high C₂H₂/C₂H₄ selectivity (5.8 to 7.7 at 273 K and 4.8 to 7.2 at 298 K). Specifically, the C₂H₂/CH₄ selectivity of ZJU-198a reaches up to 497.9 and 391.1 at 273 K and 298 K, respectively. To the best of our knowledge, the C₂H₂/CH₄ selectivity coefficients of ZJU-198a at both 298 K and 273 K are the highest values among the reported metal–organic frameworks, meaning that there is bright potential for ZJU-198a in hydrocarbon storage and separation.