1. [BMIM][OAc] coating layer makes activated carbon almost completely selective for CO2.
- Author
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Durak, Ozce, Zeeshan, Muhammad, Keskin, Seda, and Uzun, Alper
- Subjects
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POROUS materials , *CARBON dioxide , *HYDROPHOBIC surfaces , *COMPOSITE materials , *SEPARATION of gases , *ACTIVATED carbon , *MESOPOROUS materials , *COMPOSITE membranes (Chemistry) - Abstract
[Display omitted] • Ionic liquid (IL) bi-layer formation is observed after 20 wt% IL loading. • C2H site of cation becomes available with newly formed IL layer for CO 2 chemisorption. • The newly formed IL layer acts as a smart gate for selective CO 2 passage. • Pore blockage and decreased surface hydrophobicity hindered N 2 and CH 4 sorption. • At low pressures, IL 35 /AC composite material becomes almost fully selective for CO 2. Tuning the molecular affinity of porous materials towards desired gases is important to achieve superior selectivity for a target separation. Herein, we report a novel composite, prepared by coating an ordinary activated carbon (AC) with an ionic liquid (IL) (1-butyl-3-methylimidazolium acetate, [BMIM][OAc]) offering an almost complete CO 2 selectivity over N 2 and CH 4. Data indicated that pore blockage by the IL accompanied with the enhancement in polarity and reduction in the hydrophobic character of the surface hindered the sorption of N 2 and CH 4. For CO 2 , on the other hand, new chemisorption and physisorption sites became available associated with the IL layer on the surface, making the composite material significantly selective. Newly formed chemisorption sites attributed to the cation's acidic C2H sites, which become available with bi-layer formation. Presence of multiple competitive sorption sites with different energies was further proven with thermal analysis and detailed spectroscopic analysis. Data showed that CO 2 /CH 4 and CO 2 /N 2 ideal selectivities boosted from 3.3 to 688.3 (2.3 to 54.7) and from 15.6 to 903.7 (7.1 to 74.3) at 0.1 (1) bar and 25 °C, respectively, upon the deposition of IL layer. Especially at lower pressures, the IL/AC material became almost fully selective for CO 2 offering ideal selectivities in the order of several tens of thousands. To the best of our knowledge, the remarkable enhancement in the ideal CO 2 selectivity by a straightforward post-synthesis modification of an ordinary AC, as reported here, sets a new benchmark in high-performance and efficient gas separation for similar porous materials. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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