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

Purification of CH from a ternary CH/CH/CH 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 CH-selective MOF, enabling efficient one-step production of polymer-grade CH from ternary mixtures. Introduction of amino groups into highly stable CH-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 CH and CH adsorption capacities over CH. The amino-functionalized UiO-67-(NH) thus exhibits exceptionally high CH and CH uptakes as well as benchmark CH/CH and CH/CH selectivities, surpassing all of the CH/CH-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 CH and CH over CH. The exceptional performance of UiO-67-(NH) was evidenced by breakthrough experiments for CH/CH/CH mixtures under dry and wet conditions, providing a remarkable CH productivity of 0.55 mmol g at ambient conditions.