Aromatic pore surface with multiple adsorption sites for one-step C2H4 acquisition from C2H6/C2H4 mixture

Abstract

Developing a C₂H₆-selective adsorbent for the efficient one-step purification of C₂H₄ from C₂H₆/C₂H₄ mixture is of great significance but is still challenging because of the extremely close physicochemical properties of C₂H₆ and C₂H₄. We herein report a metal–organic framework Ni-3-F, which possesses an aromatic pore surface and shows high-density distribution of N/O/F atoms on its pore wall. Such a special pore environment provides the C₂H₆ molecule with multitudinous binding sites. Adsorption experiments show that Ni-3-F exhibits a higher C₂H₆ adsorption capacity than C₂H₄ in the range of 273–313 K and delivers a high C₂H₆/C₂H₄ (1/99) selectivity of 1.80 at 298 K. Practical breakthrough experiments show that Ni-3-F can achieve efficient C₂H₆/C₂H₄ separation and realize a relatively high C₂H₄ yield (27.14 L kg⁻¹) at 298 K and 1 bar. Furthermore, according to its comparatively stable structure, Ni-3-F can maintain good separation performance at different temperatures (298–318 K), flow rates (1.05–2.95 mL min⁻¹) and relative humidities (33–100%). Computational simulations reveal that the aromatic pore surface and multiple N/O/F sites comprehensively provide C₂H₆ with more C–H⋯π and C–H⋯N/O/F supramolecular interactions, which allows Ni-3-F to preferentially adsorb C₂H₆ over C₂H₄.