Important Roles of Enthalpic and Entropic Contributions to CO 2 Capture from Simulated Flue Gas and Ambient Air Using Mesoporous Silica Grafted Amines

Handle URI:
http://hdl.handle.net/10754/598575
Title:
Important Roles of Enthalpic and Entropic Contributions to CO 2 Capture from Simulated Flue Gas and Ambient Air Using Mesoporous Silica Grafted Amines
Authors:
Alkhabbaz, Mustafa A.; Bollini, Praveen; Foo, Guo Shiou; Sievers, Carsten; Jones, Christopher W.
Abstract:
© 2014 American Chemical Society. The measurement of isosteric heats of adsorption of silica supported amine materials in the low pressure range (0- 0.1 bar) is critical for understanding the interactions between CO2 and amine sites at low coverage and hence to the development of efficient amine adsorbents for CO2 capture from flue gas and ambient air. Heats of adsorption for an array of silica-supported amine materials are experimentally measured at low coverage using a Calvet calorimeter equipped with a customized dosing manifold. In a series of 3-aminopropylfunctionalized silica materials, higher amine densities resulted in higher isosteric heats of adsorption, clearly showing that the density/proximity of amine sites can influence the amine efficiency of adsorbents. In a series of materials with fixed amine loading but different amine types, strongly basic primary and secondary amine materials are shown to have essentially identical heats of adsorption near 90 kJ/mol. However, the adsorption uptakes vary substantially as a function of CO2 partial pressure for different primary and secondary amines, demonstrating that entropic contributions to adsorption may play a key role in adsorption at secondary amine sites, making adsorption at these sites less effi cient at the low coverages that are important to the direct capture of CO2 from ambient air. Thus, while primary amines are confirmed to be the most effective amine types for CO2 capture from ambient air, this is not due to enhanced enthalpic contributions associated with primary amines over secondary amines, but may be due to unfavorable entropic factors associated with organization of the second alkyl chain on the secondary amine during CO2 adsorption. Given this hypothesis, favorable entropic factors may be the main reason primary amine based adsorbents are more effective under air capture conditions.
Citation:
Alkhabbaz MA, Bollini P, Foo GS, Sievers C, Jones CW (2014) Important Roles of Enthalpic and Entropic Contributions to CO 2 Capture from Simulated Flue Gas and Ambient Air Using Mesoporous Silica Grafted Amines . Journal of the American Chemical Society 136: 13170–13173. Available: http://dx.doi.org/10.1021/ja507655x.
Publisher:
American Chemical Society (ACS)
Journal:
Journal of the American Chemical Society
KAUST Grant Number:
KUSI1-011-21
Issue Date:
24-Sep-2014
DOI:
10.1021/ja507655x
PubMed ID:
25215519
Type:
Article
ISSN:
0002-7863; 1520-5126
Sponsors:
This publication is based on work supported in part by Award KUSI1-011-21, made by King Abdullah University of Science and Technology (KAUST). The work was also supported in part by the Office of Naval Research, via ONR code 33. M.A.A. thanks the Research & Development Center of Saudi Aramco for the Ph.D. scholarship.
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Full metadata record

DC FieldValue Language
dc.contributor.authorAlkhabbaz, Mustafa A.en
dc.contributor.authorBollini, Praveenen
dc.contributor.authorFoo, Guo Shiouen
dc.contributor.authorSievers, Carstenen
dc.contributor.authorJones, Christopher W.en
dc.date.accessioned2016-02-25T13:32:26Zen
dc.date.available2016-02-25T13:32:26Zen
dc.date.issued2014-09-24en
dc.identifier.citationAlkhabbaz MA, Bollini P, Foo GS, Sievers C, Jones CW (2014) Important Roles of Enthalpic and Entropic Contributions to CO 2 Capture from Simulated Flue Gas and Ambient Air Using Mesoporous Silica Grafted Amines . Journal of the American Chemical Society 136: 13170–13173. Available: http://dx.doi.org/10.1021/ja507655x.en
dc.identifier.issn0002-7863en
dc.identifier.issn1520-5126en
dc.identifier.pmid25215519en
dc.identifier.doi10.1021/ja507655xen
dc.identifier.urihttp://hdl.handle.net/10754/598575en
dc.description.abstract© 2014 American Chemical Society. The measurement of isosteric heats of adsorption of silica supported amine materials in the low pressure range (0- 0.1 bar) is critical for understanding the interactions between CO2 and amine sites at low coverage and hence to the development of efficient amine adsorbents for CO2 capture from flue gas and ambient air. Heats of adsorption for an array of silica-supported amine materials are experimentally measured at low coverage using a Calvet calorimeter equipped with a customized dosing manifold. In a series of 3-aminopropylfunctionalized silica materials, higher amine densities resulted in higher isosteric heats of adsorption, clearly showing that the density/proximity of amine sites can influence the amine efficiency of adsorbents. In a series of materials with fixed amine loading but different amine types, strongly basic primary and secondary amine materials are shown to have essentially identical heats of adsorption near 90 kJ/mol. However, the adsorption uptakes vary substantially as a function of CO2 partial pressure for different primary and secondary amines, demonstrating that entropic contributions to adsorption may play a key role in adsorption at secondary amine sites, making adsorption at these sites less effi cient at the low coverages that are important to the direct capture of CO2 from ambient air. Thus, while primary amines are confirmed to be the most effective amine types for CO2 capture from ambient air, this is not due to enhanced enthalpic contributions associated with primary amines over secondary amines, but may be due to unfavorable entropic factors associated with organization of the second alkyl chain on the secondary amine during CO2 adsorption. Given this hypothesis, favorable entropic factors may be the main reason primary amine based adsorbents are more effective under air capture conditions.en
dc.description.sponsorshipThis publication is based on work supported in part by Award KUSI1-011-21, made by King Abdullah University of Science and Technology (KAUST). The work was also supported in part by the Office of Naval Research, via ONR code 33. M.A.A. thanks the Research & Development Center of Saudi Aramco for the Ph.D. scholarship.en
dc.publisherAmerican Chemical Society (ACS)en
dc.titleImportant Roles of Enthalpic and Entropic Contributions to CO 2 Capture from Simulated Flue Gas and Ambient Air Using Mesoporous Silica Grafted Aminesen
dc.typeArticleen
dc.identifier.journalJournal of the American Chemical Societyen
dc.contributor.institutionGeorgia Institute of Technology, Atlanta, United Statesen
kaust.grant.numberKUSI1-011-21en

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