The kinetics of the oxidation of ammonia on a V2O5/TiO2 SCR catalyst deactivated in an engine rig. Part I. Determination of kinetic parameters by simulation

Year 2019, , 211 - 221, 31.12.2019

İngemar Odenbrand

https://doi.org/10.35208/ert.597731

Cited By: 1

Abstract

It is shown how the
deactivation of a diesel SCR (Selective Catalytic Reduction) catalyst by
compounds in the exhaust gases influences the kinetics of the catalyst. Results
are given for the fresh (4.56 % V₂O₅/TiO₂)
catalyst and the ones used in the rig for 890 h and 2299 h. The reactions of
700 ppm NH₃ and 2 % O₂ in Helium yielded N₂, N₂O,
and NO at increasing temperatures. Simulations were performed with COMSOL
Multiphysics using a 3-D model of the catalyst system. The experimental values
of the products N₂, N₂O, and NO were very nicely fitted
by the kinetic model used. All three ammonia oxidation reaction rates were of
the first order in the concentration of NH₃. A preliminary study
using non-isothermal conditions showed the maximal temperature increase to be
0.15 K. Thus, further simulations were done with an isothermal model. The
deactivation reduces the pre-exponential factors and the activation energies
for the formation of N₂, N₂O, and NO. The formation of N₂
is not substantially influenced by deactivation. The changes in the kinetics of
the catalytic NH₃ oxidation by deactivation is reported for the
first time in the present study.

Keywords

Oxidation of ammonia, poisoning and kinetics, Vanadia SCR diesel catalysts

Supporting Institution

Department of Chemical Engineering

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