Single‐Phase Covalent Organic Framework Staggered Stacking Nanosheet Membrane for CO2‐Selective Separation

Two‐dimensional covalent organic frameworks (2D COFs) are considered as potential candidates for gas separation membranes, benefiting from permanent porosity, light‐weight skeletons, excellent stability and facilely‐tailored functionalities. However, their pore sizes are generally larger than the ki...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2021-08, Vol.60 (35), p.19047-19052
Main Authors: Wang, Pengyuan, Peng, Yuan, Zhu, Chenyu, Yao, Rui, Song, Hongling, Kun, Lun, Yang, Weishen
Format: Article
Language:English
Subjects:
Carbon dioxide
CO2-selective separation
covalent organic frameworks
Diameters
Fabrication
Gas permeation
Gas separation
Membranes
Nanosheets
Pore size
Porosity
Selective adsorption
Stacking
staggered stacking
Synthesis gas
two-dimensional membranes
Weight reduction
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Summary:Two‐dimensional covalent organic frameworks (2D COFs) are considered as potential candidates for gas separation membranes, benefiting from permanent porosity, light‐weight skeletons, excellent stability and facilely‐tailored functionalities. However, their pore sizes are generally larger than the kinetic diameters of common gas molecules. One great challenge is the fabrication of single‐phase COF membranes to realize precise gas separations. Herein, three kinds of high‐quality β‐ketoenamine‐type COF nanosheets with different pore sizes were developed and aggregated to ultrathin nanosheet membranes with distinctive staggered stacking patterns. The narrowed pore sizes derived from the micro‐structures and selective adsorption capacities synergistically endowed the COF membranes with intriguing CO2‐philic separation performances, among which TpPa‐2 with medium pore size exhibited an optimal CO2/H2 separation factor of 22 and a CO2 permeance of 328 gas permeation units at 298 K. This membrane performance reached the target with commercial feasibility for syngas separations. Three kinds of lamellar COFs were exfoliated into discrete nanosheets with large aspect‐ratios. The nanosheets were assembled into ultrathin two‐dimensional membranes with staggered stacking patterns, respectively. Taking advantage of narrowed pore size and CO2‐philic adsorption, these single‐phase COF nanosheet membranes were characterized by superior CO2/H2 separation performances.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202106346