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Topics in Catalysis

, Volume 42, Issue 1–4, pp 123–127 | Cite as

Modeling mass transport with microkinetics in monolithic NO x storage and reduction catalyst

  • Björn Wickman
  • Andreas Lundström
  • Jonas SjöblomEmail author
  • Derek Creaser
Article

A 2D axisymetric model of a NO x storage and reduction catalyst monolith channel combining mass transport with a detailed kinetic model was created to evaluate the importance of mass transport in a Pt/BaO/Al2O3 washcoat. Results show that there are small radial gradients in stored species concentration early during transients. The Sherwood number calculated during the transient storage phase will not be constant in time nor space as a film correlation would predict, but instead shows a region of higher Sherwood number propagating through the channel as the storage reaches completion. It is concluded that incorporating detailed mass transport provides a better spatially resolved picture of the dynamics of the proposed reaction mechanism and minimises the risk of arriving at false intrinsic kinetics during the development of a microkinetic model.

Keywords

Transient 2D microkinetic modeling washcoat Pt/BaO/Al2O3 NSR 

Symbols

u

Velocity, m/s

c

Concentration, mol/m3

T

Temperature, K

p

Pressure, Pa

η

Viscosity, Pa s

D

Diffusivity, m2/s

k

Thermal conductivity, W/(m K)

t

Time, s

ρ

Density, kg/m3

Cp

Heat capacity, J/(kg K)

ε

Porosity

ν

Stoichiometric coefficient

r

Rate of reaction, mol/(m3 kg catalyst)

θ

Coverage

L

Loading, mol/kg catalyst

dc

Channel diameter, m

Subscripts and Superscripts

i

Species number

j

Reaction number

0

Boundary value

s

Washcoat and Washcoat/Channel boundary

k

Type of site

b

Channel bulk

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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Björn Wickman
    • 1
  • Andreas Lundström
    • 2
  • Jonas Sjöblom
    • 2
    Email author
  • Derek Creaser
    • 2
  1. 1.Applied PhysicsChalmers University of TechnologyGothenburgSweden
  2. 2.Chemical Reaction EngineeringChalmers University of TechnologyGothenburgSweden

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