Author: ["Christian J. Doonan","David J. Tranchemontagne","T. Grant Glover","Joseph R. Hunt","Omar M. Yaghi"]
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Abstract
Covalent organic frameworks (COFs) are porous crystalline materials composed of light elements linked by strong covalent bonds. A number of these materials contain a high density of Lewis acid boron sites that can strongly interact with Lewis basic guests, which makes them ideal for the storage of corrosive chemicals such as ammonia. We found that a member of the covalent organic framework family, COF-10, shows the highest uptake capacity (15 mol kg−1, 298 K, 1 bar) of any porous material, including microporous 13X zeolite (9 mol kg−1), Amberlyst 15 (11 mol kg−1) and mesoporous silica, MCM-41 (7.9 mol kg−1). Notably, ammonia can be removed from the pores of COF-10 by heating samples at 200 °C under vacuum. In addition, repeated adsorption of ammonia into COF-10 causes a shift in the interlayer packing, which reduces its apparent surface area to nitrogen. However, owing to the strong Lewis acid–base interactions, the total uptake capacity of ammonia and the structural integrity of the COF are maintained after several cycles of adsorption/desorption. The uptake of ammonia by a covalent–organic framework (COF) containing a high density of Lewis-acidic boron sites has been found to be significantly greater than that exhibited by other state-of-the-art porous materials. The ammonia can be removed by heating under vacuum and the structural integrity of the COF is maintained during adsorption/desorption cycles. Cite this article
Doonan, C., Tranchemontagne, D., Glover, T. et al. Exceptional ammonia uptake by a covalent organic framework. Nature Chem 2, 235–238 (2010). https://doi.org/10.1038/nchem.548 