Facilitated Transport Membranes with Tunable Amine-CO<sub>2</sub> Chemistry for CO<sub>2</sub>/H<sub>2</sub> Separation [electronic resource]
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| Format: | Government Document Electronic eBook |
| Language: | English |
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Washington, D.C. : Oak Ridge, Tenn. :
United States. Office of the Assistant Secretary of Energy for Fossil Energy ; Distributed by the Office of Scientific and Technical Information, U.S. Department of Energy,
2020.
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| Abstract: | CO<sub>2</sub>-selective, amine-containing facilitated transport membranes are of great interest for syngas purification since high-pressure H<sub>2</sub> can be retained upon CO<sub>2</sub> removal. A variety of amine-containing polymers have shown decent chemical and thermal stability at aggressive conditions, but their CO<sub>2</sub>/H<sub>2</sub> separation properties are largely limited by the hydrostatic compaction and severe carrier saturation associated with the high syngas pressure. Herein, we report a new approach to enhance the CO<sub>2</sub> permeability by manipulating the steric hindrance of the amine carriers. A series of ?-aminoacids with different alkyl or hydroxyethyl substituents are deprotonated by 2-(1-piperazinyl)ethylamine, leading to nonvolatile amine carriers with different degrees of steric hindrance. For hosting the low MW amine carriers, a highly crosslinked poly(vinyl acetal) is synthesized as a water-swellable polymer network. In order to avoid membrane compaction, perforated graphene oxide mono-sheets are dispersed as reinforcement fillers. In the presence of moisture, a bulkier alkyl substituent to the amino site (increasing steric hindrance) destabilizes the carbamate adduct and thus drastically increases the chemisorption of CO<sub>2</sub>, while the incorporation of ethylene oxide groups provides additional physisorption of CO<sub>2</sub>. The enhanced CO<sub>2</sub> solubility significantly mitigates the carrier saturation behavior, and an unprecedented CO<sub>2</sub>/H<sub>2</sub> selectivity greater than 100 is demonstrated at 107 ʻC and 12.5 atm of CO<sub>2</sub> partial pressure. As the CO<sub>2</sub> partial pressure reduces to 0.4 atm, a less hindered amine yields a higher reactive diffusivity of CO<sub>2</sub>, resulting in a CO<sub>2</sub> permeance of 435 GPU with a selectivity greater than 500. These reaction-mediated polymeric membranes are well above the theoretical upper bound, and they are of great interest for designing a highly-selective membrane process for syngas purification. |
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| Item Description: | Published through Scitech Connect. 01/29/2020. Han, Yang ; Ho, W.S. Winston ; The Ohio State Univ., Columbus, OH (United States) |
| Physical Description: | Medium: ED : digital, PDF file. |