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Microkinetic modeling of the fast selective catalytic reduction of nitrogen oxide with ammonia on H-ZSM5 based on first principles
Publikationstyp
Journal Article
Date Issued
2011-09-23
Sprache
English
Author(s)
Institut
Journal
Volume
283
Issue
2
Start Page
178
End Page
191
Citation
Journal of Catalysis 283 (2): 178-191 (2011)
Publisher DOI
Scopus ID
Publisher
Elsevier
The reaction mechanism of the fast selective catalytic reduction (SCR) of NOx has been investigated by means of a microkinetic model based on DFT calculations. First, potential additional reaction mechanisms are presented that include the intermediate formation of Z-[NOx] + (x = 1, 2) from the decomposition of N2Oy (y = 3, 4) on a Brønsted acid. The formed NOx+ reacts with ammonia to nirosamine or nitramide. The DFT results are applied in a microkinetic model together with prior studies of Brüggemann et al. The simulated conversion of NOx is in agreement with experimental data over a wide range of temperature. The activity of the H-ZSM5 for the fast SCR is based on the reaction sequence via Z-[NOx]+, the decomposition of nitrosamine and nitramide, and the reaction of nitrous and nitric acid with adsorbed ammonia at low temperatures. Ammonia blocks the active sites at low temperatures while thermodynamic limitations of the surface species N2Oy restrict the conversion at high temperatures. Heat of formations and reaction rate constants were adjusted within the accuracy of the applied method for important elementary steps to cope with experimental data.
Subjects
Ammonia adsorption
Ammonia oxidation
Ammonium
Fast SCR
Microkinetic modeling
Nitramide
Nitrosamine
Nitrosyl
NO -SCR 2
ZSM5
DDC Class
540: Chemie
660: Technische Chemie