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High Temperature and High Concentration SCR of NO with NH3 for the Oxyfuel Combustion Process : Fitting of Kinetics to Data from a Laboratory Reactor Experiment

Odenbrand, C. U. Ingemar LU (2017) In Topics in Catalysis p.1-16
Abstract

This study shows the result of a simulation of a proposed kinetic reaction scheme of high-concentration (5000 ppm NO) and high-temperature (570–800 K) selective catalytic reduction of NO with NH3 on a commercial vanadia based catalyst at a system pressure of 2.2 bar. The simulations are performed with COMSOL Multiphysics ver. 5.1. Experimental data from a catalytic flow reactor can be nicely fitted to a system of kinetic expressions for the selective catalytic reduction (SCR) reaction and its side reactions. Especial attention is given to the formation of N2O. All reaction rate expressions contain an ammonia adsorption term. The value for its pre-exponential factor is 9e−9 and its activation energy is −139 kJ/mol.... (More)

This study shows the result of a simulation of a proposed kinetic reaction scheme of high-concentration (5000 ppm NO) and high-temperature (570–800 K) selective catalytic reduction of NO with NH3 on a commercial vanadia based catalyst at a system pressure of 2.2 bar. The simulations are performed with COMSOL Multiphysics ver. 5.1. Experimental data from a catalytic flow reactor can be nicely fitted to a system of kinetic expressions for the selective catalytic reduction (SCR) reaction and its side reactions. Especial attention is given to the formation of N2O. All reaction rate expressions contain an ammonia adsorption term. The value for its pre-exponential factor is 9e−9 and its activation energy is −139 kJ/mol. The fastest reaction is the standard SCR reaction with a pre-exponential factor of 5.28e7 s−1 and an activation energy of 85 kJ/mol. This reaction is affected by internal diffusion limitations. The oxidation of NH3 to NO is the second fastest reaction with parameters 5e12 mol/m3s and 200 kJ/mol. The NSCR of NH3 to N2O is the third fastest reaction with values of 7.5e5 s−1 and 110 kJ/mol. The oxidation of NH3 to N2O has the parameters 8e11 mol/m3/s and 190 kJ/mol. At 640 K inlet temperature the rate of the SCR reaction is about 1.3 mol/m3/s. The oxidation of NH3 to NO is 4.7e−4 mol/m3/s. The rate of the NSCR producing N2O is 1.63e−4 mol/m3/s. The rate of the direct oxidation of NH3 to N2O is 3.7e−5 mol/m3/s. Thus the rate of the SCR reaction is about 35,000 faster than the high temperature production of N2O at this temperature.

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author
organization
publishing date
type
Contribution to journal
publication status
epub
subject
keywords
Fitting of experimental data, High concentration, High temperature, Kinetics, Oxyfuel process, SCR
in
Topics in Catalysis
pages
16 pages
publisher
Kluwer
external identifiers
  • scopus:85020475847
ISSN
1022-5528
DOI
10.1007/s11244-017-0817-x
language
English
LU publication?
yes
id
46da1be5-8256-40fd-8043-9935d088c2a2
date added to LUP
2017-06-26 16:10:15
date last changed
2017-06-26 16:10:15
@article{46da1be5-8256-40fd-8043-9935d088c2a2,
  abstract     = {<p>This study shows the result of a simulation of a proposed kinetic reaction scheme of high-concentration (5000 ppm NO) and high-temperature (570–800 K) selective catalytic reduction of NO with NH<sub>3</sub> on a commercial vanadia based catalyst at a system pressure of 2.2 bar. The simulations are performed with COMSOL Multiphysics ver. 5.1. Experimental data from a catalytic flow reactor can be nicely fitted to a system of kinetic expressions for the selective catalytic reduction (SCR) reaction and its side reactions. Especial attention is given to the formation of N<sub>2</sub>O. All reaction rate expressions contain an ammonia adsorption term. The value for its pre-exponential factor is 9e−9 and its activation energy is −139 kJ/mol. The fastest reaction is the standard SCR reaction with a pre-exponential factor of 5.28e7 s<sup>−1</sup> and an activation energy of 85 kJ/mol. This reaction is affected by internal diffusion limitations. The oxidation of NH<sub>3</sub> to NO is the second fastest reaction with parameters 5e12 mol/m<sup>3</sup>s and 200 kJ/mol. The NSCR of NH<sub>3</sub> to N<sub>2</sub>O is the third fastest reaction with values of 7.5e5 s<sup>−1</sup> and 110 kJ/mol. The oxidation of NH<sub>3</sub> to N<sub>2</sub>O has the parameters 8e11 mol/m<sup>3</sup>/s and 190 kJ/mol. At 640 K inlet temperature the rate of the SCR reaction is about 1.3 mol/m<sup>3</sup>/s. The oxidation of NH<sub>3</sub> to NO is 4.7e−4 mol/m<sup>3</sup>/s. The rate of the NSCR producing N<sub>2</sub>O is 1.63e−4 mol/m<sup>3</sup>/s. The rate of the direct oxidation of NH<sub>3</sub> to N<sub>2</sub>O is 3.7e−5 mol/m<sup>3</sup>/s. Thus the rate of the SCR reaction is about 35,000 faster than the high temperature production of N<sub>2</sub>O at this temperature.</p>},
  author       = {Odenbrand, C. U. Ingemar},
  issn         = {1022-5528},
  keyword      = {Fitting of experimental data,High concentration,High temperature,Kinetics,Oxyfuel process,SCR},
  language     = {eng},
  month        = {06},
  pages        = {1--16},
  publisher    = {Kluwer},
  series       = {Topics in Catalysis},
  title        = {High Temperature and High Concentration SCR of NO with NH<sub>3</sub> for the Oxyfuel Combustion Process : Fitting of Kinetics to Data from a Laboratory Reactor Experiment},
  url          = {http://dx.doi.org/10.1007/s11244-017-0817-x},
  year         = {2017},
}