Carbon Dioxide Capture at Nucleophilic Hydroxide Sites in Oxidation‐Resistant Cyclodextrin‐Based Metal–Organic Frameworks

• Published in: Angewandte Chemie (International ed.) 2022-07, Vol.61 (30), p.e202206718-n/a
• Main Authors: Zick, Mary E., Pugh, Suzi M., Lee, Jung‐Hoon, Forse, Alexander C., Milner, Phillip J.
• Format: Article
• Language: English
• Subjects: Adsorption; Cadmium; Carbon dioxide; Carbon sequestration; Carbon Storage; Chemisorption; Climate change; Cyclodextrin; Cyclodextrins; Hydrogen Bonds; Metal-organic frameworks; NMR Spectroscopy; Oxidation; Oxidation resistance; Sorbents
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202206718

Carbon capture and sequestration (CCS) from industrial point sources and direct air capture are necessary to combat global climate change. A particular challenge faced by amine‐based sorbents—the current leading technology—is poor stability towards O2. Here, we demonstrate that CO2 chemisorption in γ‐cylodextrin‐based metal–organic frameworks (CD‐MOFs) occurs via HCO3− formation at nucleophilic OH− sites within the framework pores, rather than via previously proposed pathways. The new framework KHCO3 CD‐MOF possesses rapid and high‐capacity CO2 uptake, good thermal, oxidative, and cycling stabilities, and selective CO2 capture under mixed gas conditions. Because of its low cost and performance under realistic conditions, KHCO3 CD‐MOF is a promising new platform for CCS. More broadly, our work demonstrates that the encapsulation of reactive OH− sites within a porous framework represents a potentially general strategy for the design of oxidation‐resistant adsorbents for CO2 capture. Carbon capture and sequestration is needed to fight global climate change, but current technologies are largely limited to sorbents based on oxidatively sensitive amines. Hydroxides encapsulated within cyclodextrin‐based metal–organic frameworks are demonstrated to capture CO2 via reversible bicarbonate formation, leading to a promising oxidatively stable class of materials for CO2 capture from industrial point sources.