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The role of K2O in the selective reduction of NO with NH3 over a V2O5(WO3)/TiO2 commercial selective catalytic reduction catalyst

Kamata, H; Takahashi, K and Odenbrand, Ingemar LU (1999) In Journal of Molecular Catalysis A: Chemical 139(2-3). p.189-198
Abstract
To elucidate the nature of the acid sites of the V2O5(WO3)/TiO2 catalyst upon K2O addition and its relation to the selective reduction of NO with NH3, measurements were made by means of infrared and Raman spectroscopy, NH3 chemisorption, and NO reduction measurements as a function of the K2O loading. The catalytic activity was found to decrease rapidly with the K2O loading, irrespective of the similar textural properties of all samples. Addition of K2O modified the vanadium species on the catalyst surface. For large additions of K2O, the potassium partially reacted with V2O5 to form KVO3. The amount of NH3 chemisorbed on the catalyst was observed to decrease with both the loading of K2O and the temperature. The adsorption of NH3 on both... (More)
To elucidate the nature of the acid sites of the V2O5(WO3)/TiO2 catalyst upon K2O addition and its relation to the selective reduction of NO with NH3, measurements were made by means of infrared and Raman spectroscopy, NH3 chemisorption, and NO reduction measurements as a function of the K2O loading. The catalytic activity was found to decrease rapidly with the K2O loading, irrespective of the similar textural properties of all samples. Addition of K2O modified the vanadium species on the catalyst surface. For large additions of K2O, the potassium partially reacted with V2O5 to form KVO3. The amount of NH3 chemisorbed on the catalyst was observed to decrease with both the loading of K2O and the temperature. The adsorption of NH3 on both Bronsted and Lewis acid sites was confirmed. The strength and the number of Bronsted acid sites decrease largely with the loading of K2O in parallel with the decrease of the SCR activity, suggesting that the SCR reaction involves NH3 adsorption on the Bronsted acid sires. At low surface coverage of NH3, the isosteric heat of NH3 chemisorption was determined to be 370 kJ/mol for 0 wt.% K2O addition. With increasing K2O amount, the heat of adsorption decreased and was 150 kJ/mol for the catalyst with higher amounts of K2O addition. The results obtained imply that potassium disturbs the formation of the active ammonia intermediates, NH4+, resulting in deactivation of the catalyst. (C) 1999 Elsevier Science B.V. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
SCR reaction, commercial catalysts, potassium oxide, ammonia adsorption, poisoning
in
Journal of Molecular Catalysis A: Chemical
volume
139
issue
2-3
pages
189 - 198
publisher
Elsevier
external identifiers
  • wos:000078361700009
  • scopus:0033525372
ISSN
1381-1169
DOI
10.1016/S1381-1169(98)00177-0
language
English
LU publication?
yes
id
d023cd55-4521-49c1-8724-dfb6b93d719b (old id 3916338)
date added to LUP
2013-07-02 14:21:05
date last changed
2017-08-13 04:19:12
@article{d023cd55-4521-49c1-8724-dfb6b93d719b,
  abstract     = {To elucidate the nature of the acid sites of the V2O5(WO3)/TiO2 catalyst upon K2O addition and its relation to the selective reduction of NO with NH3, measurements were made by means of infrared and Raman spectroscopy, NH3 chemisorption, and NO reduction measurements as a function of the K2O loading. The catalytic activity was found to decrease rapidly with the K2O loading, irrespective of the similar textural properties of all samples. Addition of K2O modified the vanadium species on the catalyst surface. For large additions of K2O, the potassium partially reacted with V2O5 to form KVO3. The amount of NH3 chemisorbed on the catalyst was observed to decrease with both the loading of K2O and the temperature. The adsorption of NH3 on both Bronsted and Lewis acid sites was confirmed. The strength and the number of Bronsted acid sites decrease largely with the loading of K2O in parallel with the decrease of the SCR activity, suggesting that the SCR reaction involves NH3 adsorption on the Bronsted acid sires. At low surface coverage of NH3, the isosteric heat of NH3 chemisorption was determined to be 370 kJ/mol for 0 wt.% K2O addition. With increasing K2O amount, the heat of adsorption decreased and was 150 kJ/mol for the catalyst with higher amounts of K2O addition. The results obtained imply that potassium disturbs the formation of the active ammonia intermediates, NH4+, resulting in deactivation of the catalyst. (C) 1999 Elsevier Science B.V. All rights reserved.},
  author       = {Kamata, H and Takahashi, K and Odenbrand, Ingemar},
  issn         = {1381-1169},
  keyword      = {SCR reaction,commercial catalysts,potassium oxide,ammonia adsorption,poisoning},
  language     = {eng},
  number       = {2-3},
  pages        = {189--198},
  publisher    = {Elsevier},
  series       = {Journal of Molecular Catalysis A: Chemical},
  title        = {The role of K2O in the selective reduction of NO with NH3 over a V2O5(WO3)/TiO2 commercial selective catalytic reduction catalyst},
  url          = {http://dx.doi.org/10.1016/S1381-1169(98)00177-0},
  volume       = {139},
  year         = {1999},
}