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First-Principles Ca...
First-Principles Calculations of Condition-Dependent Cu/Fe Speciation in Sulfur-Poisoned Cu- and Fe-SSZ-13 Catalysts
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- Mesilov, Vitaly (författare)
- Yale NUS Coll, Sci Div, Singapore 138527, Singapore.
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- Xiao, Yang (författare)
- Yale NUS Coll, Sci Div, Singapore 138527, Singapore.
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- Dahlin, Sandra (författare)
- KTH,Processteknologi
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- Bergman, Susanna L. (författare)
- Yale NUS Coll, Sci Div, Singapore 138527, Singapore.
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- Pettersson, Lars (författare)
- KTH,Processteknologi
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- Bernasek, Steven L. (författare)
- Yale NUS Coll, Sci Div, Singapore 138527, Singapore.
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Yale NUS Coll, Sci Div, Singapore 138527, Singapore Processteknologi (creator_code:org_t)
- 2021-02-17
- 2021
- Engelska.
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 125:8, s. 4632-4645
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
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- A combination of first-principles thermodynamics and density functional theory (DFT) was applied for the prediction of sulfur-poisoned monomeric Cu/Fe species formed in the SSZ-13 catalyst framework under selective catalytic reduction (SCR)-relevant conditions in the presence of sulfur dioxide, ammonia, oxygen, and water. Differences in fresh and sulfur-poisoned species were found for Cu- and Fe-SSZ-13 catalysts containing one Al (1Al sites) or two Al (2Al sites) in 6-membered rings (6MRs) or 8-membered rings (8MRs). The impact of ammonia concentration during low-and high-temperature sulfur-poisoning on Cu- and Fe-speciation was also investigated. SCR-relevant concentrations of ammonia in the gas mixture led to the formation of ammonium sulfates over copper in 2Al and 1Al sites of Cu-SSZ-13, while bisulfate and sulfuric acid species were predicted at these copper sites either in the absence of ammonia or at negligible concentrations of ammonia during low- and high-temperature poisoning. The absence of ammonia in the gas mixture led to the formation of iron-bisulfates at 2Al sites of Fe-SSZ-13 during low- temperature poisoning, while the formation of ammonium sulfates was favorable under SCR-relevant conditions. In contrast to the facile formation of ammonium sulfates at copper sites of Cu-SSZ-13, only ammonium-free iron-sulfates formed at 1Al sites in Fe-SSZ-13 under realistic operational conditions. The regeneration of 2Al sites of Cu-SSZ-13 was predicted to occur at higher temperatures compared to 2Al sites in Fe-SSZ-13, whereas the opposite was predicted for 1Al sites. The analysis of fresh and regenerated Cu/Fe species was carried out as well. These theoretical results on model catalysts provide a first step in the understanding of sulfur-poisoning in Fe-SSZ-13 catalysts, supporting further experimental investigations to improve NH3-SCR catalysts for meeting future emission standards.
Ämnesord
- TEKNIK OCH TEKNOLOGIER -- Kemiteknik (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Chemical Engineering (hsv//eng)
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