Immobilization of Lewis Basic Sites into a Stable Ethane-Selective MOF Enabling One-Step Separation of Ethylene from...

Purification of C₂H₄ from a ternary C₂H₂/C₂H₆/C₂H₄ mixture by one-step adsorption separation is of prime importance but challenging in the petrochemical industry; however, effective strategies to design high-performance adsorbents are lacking. We herein report for the first time the incorporation of Lewis basic sites into a C₂H₆-selective MOF, enabling efficient one-step production of polymer-grade C₂H₄ from ternary mixtures. Introduction of amino groups into highly stable C₂H₆-selective UiO-67 can not only partition large pores into smaller cagelike pockets to provide suitable pore confinement but also offer additional binding sites to simultaneously enhance C₂H₂ and C₂H₆ adsorption capacities over C₂H₄. The amino-functionalized UiO-67-(NH₂)₂ thus exhibits exceptionally high C₂H₂ and C₂H₆ uptakes as well as benchmark C₂H₂/C₂H₄ and C₂H₆/C₂H₄ selectivities, surpassing all of the C₂H₂/C₂H₆-selective materials reported so far. Theoretical calculations combined with in situ infrared spectroscopy indicate that the synergetic effect of suitable pore confinement and functional surfaces decorated with amino groups provides overall stronger multipoint van der Waals interactions with C₂H₂ and C₂H₆ over C₂H₄. The exceptional performance of UiO-67-(NH₂)₂ was evidenced by breakthrough experiments for C₂H₂/C₂H₆/C₂H₄ mixtures under dry and wet conditions, providing a remarkable C₂H₄ productivity of 0.55 mmol g^-1 at ambient conditions.