Lim S Alexandra, Zick Mary E, Kim Jaehwan, Rhodes Benjamin J, Randrianandraina Joharimanitra, Pitt Tristan A, Jerozal Ronald T, Lee Jung-Hoon, Forse Alexander C, Milner Phillip J
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States.
Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K.
J Am Chem Soc. 2025 Jul 23;147(29):25715-25726. doi: 10.1021/jacs.5c07336. Epub 2025 Jul 10.
Carbon capture and utilization or sequestration (CCUS) from industrial point sources and direct air capture (DAC) are both necessary to curb the rising atmospheric levels of CO. Amine scrubbers, the current leading carbon capture technology, suffer from poor oxidative and thermal stability, limiting their long-term cycling stability under oxygen-rich streams such as air and the emissions from natural gas combined cycle (NGCC) power plants. Herein, we demonstrate that the hydroxide-based cyclodextrin metal-organic framework (CD-MOF) RbCO CD-MOF ST possesses high CO capacities from dry dilute streams at low temperatures and humid streams at elevated temperatures. Additionally, it displays good thermal, oxidative, and cycling stabilities and selective CO capture under mixed gas conditions in dynamic breakthrough experiments. Unexpectedly, under dry, hot conditions, a shift in the CO adsorption mechanism─from reversibly formed bicarbonate to irreversibly formed carbonate─is observed, as supported by gas sorption and spectroscopic studies coupled with density functional theory (DFT) calculations. This mechanistic switch, akin to urea formation in amine-functionalized sorbents, has not been previously reported in a hydroxide-based material and sheds new light on the interplay between bicarbonate and carbonate species during CO capture. Our findings provide valuable insight for the design of next-generation materials containing oxygen-based nucleophiles for carbon capture applications.
来自工业点源的碳捕获与利用或封存（CCUS）以及直接空气捕获（DAC）对于遏制大气中不断上升的一氧化碳水平都是必要的。胺洗涤器作为目前领先的碳捕获技术，存在氧化稳定性和热稳定性差的问题，这限制了它们在富氧气流（如空气和天然气联合循环（NGCC）发电厂的排放物）下的长期循环稳定性。在此，我们证明基于氢氧化物的环糊精金属有机框架（CD-MOF）RbCO CD-MOF ST在低温下的干燥稀气流和高温下的潮湿气流中都具有高的一氧化碳捕获能力。此外，在动态突破实验中，它在混合气体条件下表现出良好的热稳定性、氧化稳定性和循环稳定性以及对一氧化碳的选择性捕获。出乎意料的是，在干燥、高温条件下，观察到一氧化碳吸附机制发生了转变——从可逆形成的碳酸氢盐转变为不可逆形成的碳酸盐——这得到了气体吸附和光谱研究以及密度泛函理论（DFT）计算的支持。这种机制转变类似于胺官能化吸附剂中尿素的形成，此前在基于氢氧化物的材料中尚未有报道，为一氧化碳捕获过程中碳酸氢盐和碳酸盐物种之间的相互作用提供了新的见解。我们的研究结果为设计用于碳捕获应用的含氧基亲核试剂的下一代材料提供了有价值的见解。
