Covalent Organic Frameworks for Carbon Dioxide Capture from Air

Abstract

We report the first covalent incorporation of reactive aliphatic amine species into covalent organic frameworks (COFs). This was achieved through the crystallization of an iminelinked COF, termed COF-609-Im, followed by conversion of its imine linkage to base-stable tetrahydroquinoline linkage through aza-Diels−Alder cycloaddition, and finally, the covalent incorporation of tris(3-aminopropyl)amine into the framework. The obtained COF-609 exhibits a 1360-fold increase in CO 2 uptake capacity compared to the pristine framework and a further 29% enhancement in the presence of humidity. We confirmed the chemistry of framework conversion and corroborated the enhanced CO 2 uptake phenomenon with and without humidity through isotope-labeled Fourier transform infrared spectroscopy and solidstate nuclear magnetic resonance spectroscopy. With this study, we established a new synthetic strategy to access a class of chemisorbents characterized by high affinity to CO 2 in dilute sources, such as the air.

Evaluation of amine-based solid adsorbents for direct air capture: a critical review

“…Clearly, amine-based adsorbents synthesized through in situ polymerization offer a better advantage over amine-impregnated or amine-grafted adsorbents, and further exploration for DAC application is necessary, as their bulk production is easy and energy-efficient. 111 Recently, Lyu et al 122 reported the first amine functionalized covalent organic frameworks (COFs) termed COF-609 by incorporation of an aliphatic amine such as tris(3-aminopropyl)amine into the framework. The CO 2 uptake capacity of COF-609 was found to be 0.393 mmol g −1 under simulated air containing 400 ppm CO 2 (50% RH, 25 °C and 1 atm), which is more than dry CO 2 uptake, demonstrating the efficiency of COF-609 for efficient CO 2 uptake from very diluted sources under humid condition.…”

Potassium Silicate as Low-Temperature Binder in 3D-Printed Porous Structures for CO2 Separation

“…Common adsorbent materials typically involve porous materials due to their high specific surface area and high adsorption capacities. Two categories can be distinguished, based on their adsorption process: (I) activated carbon, , zeolites, , and porous polymers, , metal organic frameworks (MOFs), , and covalent organic frameworks (COFs), , in which adsorption occurs mainly due to physisorption and (II) metal-based adsorbents (e.g., Na 2 CO 3 , K 2 CO 3 , CaO, ...) , and hybrid organic/inorganic sorbents including amine-functionalized polymers or inert supports, , in which adsorption occurs due to chemisorption. Metal-based adsorbents and specifically carbonates provide several advantages that make them desirable for carbon capture, including their inexpensiveness, nonvolatility, resistance to degradation, and low binding energy with CO 2 enabling an energy-efficient capture process.…”

Enhanced Carbon Capture Behavior of Carbon Fibers via Ionic Liquid Modification

“…Solid sorbents for CO 2 chemisorption are mainly strong basic metal oxides (e. g., CaO and MgO) [10] and amine‐functionalized (e. g., polyethyleneimine (PEI)) porous materials, [5] and the former are deployed in high‐temperature carbon capture procedures. Comparatively, amine‐modification is widely used to afford porous solid materials capable of absorbing low‐concentration CO 2 , particularly in direct air capture of CO 2 (∼400 ppm) [23–26] . Notably, besides the amine‐based moieties, ionic liquids (ILs) are another promising candidate to functionalize the porous scaffolds towards enhanced CO 2 chemisorption considering their unique features of good thermal stability, negligible vapor pressure, structure diversity, and corresponding large tuning space in their physiochemical properties towards specific CO 2 sources [27–28] .…”

“…Comparatively, amine-modification is widely used to afford porous solid materials capable of absorbing lowconcentration CO 2 , particularly in direct air capture of CO 2 (4 00 ppm). [23][24][25][26] Notably, besides the amine-based moieties, ionic liquids (ILs) are another promising candidate to functionalize the porous scaffolds towards enhanced CO 2 chemisorption considering their unique features of good thermal stability, negligible vapor pressure, structure diversity, and corresponding large tuning space in their physiochemical properties towards specific CO 2 sources. [27][28] In this aspect, the CO 2 chemisorption behavior, reaction pathways, and property variation of amino-functionalized ILs (AILs) [29][30] and superbasederived ILs (SILs) [31][32] have been extensively studied in the form of liquid sorbents.…”