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Temperature-Induced...
Temperature-Induced Uptake of CO2 and Formation of Carbamates in Mesocaged Silica Modified with n-Propylamines
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- Bacsik, Zoltan (författare)
- Stockholms universitet,Institutionen för material- och miljökemi (MMK),Stockholm University,Department of Materials and Environmental Chemistry
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- Atluri, Rambabu, 1981- (författare)
- Uppsala universitet,Nanoteknologi och funktionella material
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- Garcia-Bennett, Alfonso E. (författare)
- Uppsala universitet,Nanoteknologi och funktionella material
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- Hedin, Niklas (författare)
- Stockholms universitet,Institutionen för material- och miljökemi (MMK),Stockholm University,Department of Materials and Environmental Chemistry
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(creator_code:org_t)
- 2010-03-10
- 2010
- Engelska.
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 26:12, s. 10013-10024
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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https://urn.kb.se/re...
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Abstract
Ämnesord
Stäng
- Adsorption-mediated CO2 separation can reduce the costs of carbon capture and storage. The reduction in cost requires adsorbents with high capacities for CO2 sorption and high CO2-over-N2 selectivity. Amine-modified sorbents are promising candidates for carbon capture. To investigate the details of CO2 adsorption in such materials, we studied mesocaged (cubic, Pm3n symmetry) silica adsorbents with tethered propylamines using Fourier transform infrared (FTIR) spectroscopy and volumetric uptake experiments. The degree of heterogeneity in these coatings was varied by either co-synthesizing or post-synthetically introducing the propylamine modification. In situ FTIR spectroscopy revealed the presence of both physisorbed and chemisorbed CO2 in the materials. We present the first direct molecular evidence for physisorption using FTIR spectroscopy in mesoporous silica sorbents modified with propylamines. Physisorption reduced the CO2-over-N2 selectivity in amine-rich sorbents. Samples with homogenous coatings showed typical CO2 adsorption trends and large quantities of IR-observable physisorbed CO2. The uptake of CO2 in mesocaged materials with heterogeneous propylamine coatings was higher at high temperatures than at low temperatures. At higher temperatures and low pressures, the post-synthetically modified materials adsorbed more CO2 than did the extracted ones, even though the surface area after modification was clearly reduced and the coverage of primary amine groups was lower. The principal mode of CO2 uptake in post-synthetically modified mesoporous silica was chemisorption. The chemisorbed moieties were present mainly as carbamate–ammonium ion pairs, resulting from the quantitative transformation of primary amine groups during CO2 adsorption as established by NIR spectroscopy. The heterogeneity in the coatings promoted the formation of these ion pairs. The average propylamine–propylamine distance must be small to allow the formation of carbamate–propylammonium ion pairs.
Ämnesord
- TEKNIK OCH TEKNOLOGIER -- Materialteknik (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Materials Engineering (hsv//eng)
Nyckelord
- carbon dioxide
- propylamine
- adsorption
- IR
- FTIR
- silica
- mesoporous
- Materials science
- Teknisk materialvetenskap
- Materialvetenskap
- Materials Science
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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