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

Abstract

Purification of C 2 H 4 from a ternary C 2 H 2 /C 2 H 6 /C 2 H 4 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 C 2 H 6 -selective MOF, enabling efficient one-step production of polymer-grade C 2 H 4 from ternary mixtures. Introduction of amino groups into highly stable C 2 H 6 -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 C 2 H 2 and C 2 H 6 adsorption capacities over C 2 H 4 . The amino-functionalized UiO-67-(NH 2 ) 2 thus exhibits exceptionally high C 2 H 2 and C 2 H 6 uptakes as well as benchmark C 2 H 2 /C 2 H 4 and C 2 H 6 /C 2 H 4 selectivities, surpassing all of the C 2 H 2 /C 2 H 6 -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 C 2 H 2 and C 2 H 6 over C 2 H 4 . The exceptional performance of UiO-67-(NH 2 ) 2 was evidenced by breakthrough experiments for C 2 H 2 /C 2 H 6 /C 2 H 4 mixtures under dry and wet conditions, providing a remarkable C 2 H 4 productivity of 0.55 mmol g −1 at ambient conditions.

One‐Step C2H4Purification from Ternary C2H6/C2H4/C2H2Mixtures by a Robust Metal–Organic Framework with Customized Pore Environment

“…Recently, Li et al. reported the incorporation of Lewis basic sites into a C 2 H 6 ‐selective MOF (UiO‐67 (NH 2 ) 2 ), enabling efficient one‐step production of polymer‐grade C 2 H 4 from C 2 H 2 /C 2 H 4 /C 2 H 6 mixtures [10h] . From the viewpoints in these results, the construction of novel MOFs that selectively adsorb C 2 H 2 and C 2 H 6 over C 2 H 4 is expected not only to be used to solve the separation of multi‐component gas mixtures, but also to facilitate the understanding of specific gas molecule binding sites in MOFs.…”

Two isostructural metal–organic frameworks with unique nickel clusters for C2H2/C2H6/C2H4 mixture separation

“…The C 2 H 2 /C 2 H 4 and C 2 H 6 /C 2 H 4 selectivity was calculated to be 1.82 and 1.15 at 298 K according to the ideal adsorption solution theory (IAST). 46 The adsorption selectivity and Q st for 26 NUM-9a (1.5), 30 Azole-Th-1, 31 NPU-1 (1.4), 32 UiO-67-(NH 2 ) 2 (2.1), 28 and Zn-atz-oba (1.43). 34 To promote C 2 H 6 /C 2 H 4 selectivity and ternary separation performance, we extended the conjugation of the linker to enhance the C-H/p interaction.…”

“…Li et al recently reported MOFimmobilized basic sites to promote the C 2 H 2 /C 2 H 4 selectivity. 28 Incorporation of open metal sites could potentially enhance the acetylene adsorption to promote the C 2 H 2 /C 2 H 4 selectivity, and subsequently maximize the overall separation performance, which has rarely been reported. 29 Herein, we report two isostructural MOFs with unique open nickel sites, BUT-150 (Ni 2 (m 2 -OH 2 )DiBP 4 , DiBP ¼ 5,5ʹ-([2,2 0bipyridine]-5,5 0 -diyl)diisophthalate) and BUT-151 (Ni 2 (m 2 -OH 2 ) DiPhen 4 , DiPhen ¼ 5,5ʹ-(1,10-phenanthroline-3,8-diyl) diisophthalate).…”

Transport tuning strategies in MOF film synthesis – a perspective

“…For example, in the case of ethane/ethylene separation, which has almost similar chemical and physical properties, researchers have shown that polar groups such as sulfonate, peruoro and amino groups help in the separation of these light hydrocarbons. [41][42][43] Different functional groups are also used to introduce hydrophobicity in the structure. For example, small alkane chains have been used to introduce hydrophobicity into MOFs, allowing for much better hydrostability.…”