Carbon Dioxide Capture at Nucleophilic Hydroxide Sites in Oxidation-Resistant Cyclodextrin-Based Metal-Organic Frameworks.

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 O ₂ . Here, we demonstrate that CO ₂ chemisorption in γ-cylodextrin-based metal-organic frameworks (CD-MOFs) occurs via HCO ₃ ^- formation at nucleophilic OH ^- sites within the framework pores, rather than via previously proposed pathways. The new framework KHCO ₃ CD-MOF possesses rapid and high-capacity CO ₂ uptake, good thermal, oxidative, and cycling stabilities, and selective CO ₂ capture under mixed gas conditions. Because of its low cost and performance under realistic conditions, KHCO ₃ 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 CO ₂ capture.
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