Bottom-Up Synthesis of 8-Connected Three-Dimensional Covalent Organic Frameworks for Highly Efficient Ethylene/Ethane Separation

Abstract

Developing cost-/energy-efficient separation techniques for purifying ethylene from an ethylene/ethane mixture is highly important but very challenging in the industrial process. Herein, using a bottom-up [8 + 2] construction approach, we rationally designed and synthesized three three-dimensional covalent organic frameworks (COFs) with 8-connected bcu networks, which can selectively remove ethane from an ethylene/ethane mixture with high efficiency. These COF materials, which are fabricated by the condensation reaction of a customer-designed octatopic aldehyde monomer with linear diamino linkers, possess high crystallinity, good structural robustness, and high porosity. Attributed to the well-organized micro-sized pores with a nonpolar/inert pore environment, these COFs display high ethane adsorption capacity and good selectivity over ethylene, making them among the best ethane-selective adsorbents for ethylene purification. Their excellent ethylene/ethane separation performance is validated by dynamic breakthrough experiments with high-purity ethylene (>99.99%) produced through a single adsorption process. The separation performance surpasses all reported C2H6-selective COFs and even some benchmark metal–organic frameworks. This work provides important guidance for the design of new adsorbents for value-added gas purification.

In Situ Growth of Covalent Organic Framework Nanosheets on Graphene as the Cathode for Long‐Life High‐Capacity Lithium‐Ion Batteries

“…Polymerization of the redoxactive small molecules, [14] preparation of organic salts, [2] hybridization with insoluble materials, [15,16] and development of solid electrolytes [17,18] have been demonstrated to effectively resist dissolution. In this direction, a huge challenge toward improving electronic and ionic conductivities of organic electrode materials has aroused increasing interest in innovating the methods and materials for fabricating OMBs.Covalent organic frameworks (COFs) represent a special type of porous organic polymers because of their definite structures, good crystallinity, vast porosity, and various functions such as gas separation and storage, [19][20][21] catalysis, [22][23][24][25] proton/ion conduction, [26][27][28] and energy storage and conversion. [29][30][31] In particular, the flexible molecular design and tailoring direct the integration of redoxactive building blocks into insoluble 2D and 3D polymeric COFs depending on dynamic covalent chemistry, generating versatile organic electrode materials with excellent electrochemical activity and cycling stability.…”

“…Covalent organic frameworks (COFs) represent a special type of porous organic polymers because of their definite structures, good crystallinity, vast porosity, and various functions such as gas separation and storage, [19][20][21] catalysis, [22][23][24][25] proton/ion conduction, [26][27][28] and energy storage and conversion. [29][30][31] In particular, the flexible molecular design and tailoring direct the integration of redoxactive building blocks into insoluble 2D and 3D polymeric COFs depending on dynamic covalent chemistry, generating versatile organic electrode materials with excellent electrochemical activity and cycling stability.…”

Three-dimensional microporous and mesoporous covalent organic frameworks based on cubic building units

“…Remarkably, JUC-589 represents the first example of mesoporous COFs based on an 8-connected node and shows a higher BET surface area and pore size compared to those of similar materials reported, such as BP-COF-1 (BET: 519 m 2 g −1 and pore size: 0.6 nm), 42 and NUST-5 (BET: 680 m 2 g −1 and pore size: 1.5 nm), 43 and NKCOF-23 (BET: 1900 m 2 g −1 and pore size: 1.7 nm). 44 …”

A rigidity–flexibility balance strategy enabling highly photoluminescent two-dimensional covalent organic framework nanosheets

“…Covalent organic frameworks (COFs) are emerging as a class of crystalline polymers constructed via covalent bonds with defined topology. 1,2 The structural tunability and high degree of functionality of COFs have attracted considerable attention as promising candidates for gas storage and separation, [3][4][5] energy storage and conversion, [6][7][8] catalysis and optoelectronics. [9][10][11][12] In the context of optoelectronics, two dimensional (2D) COFs are of particular interest because the electron and exciton transporting property depends not only on their intralayer constituents but also on their interlayer structural arrangement.…”