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Diffusion limitation effects in the washcoat of a catalytic monolith reactor
Author(s) -
Leung D.,
Hayes R. E.,
Kolaczkowski S. T.
Publication year - 1996
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450740112
Subject(s) - monolith , diffusion , propane , catalysis , materials science , methane , chemical engineering , analytical chemistry (journal) , chemistry , thermodynamics , physics , chromatography , engineering , biochemistry , organic chemistry
In monolith reactors with catalytic washcoat, intraphase diffusion effects have often been underestimated. This paper presents numerical simulations of diffusion/reaction in the washcoat of a catalytic monolith reactor. The problem is solved in two dimensions for the washcoat geometry obtained in a 1‐mm square monolith channel, as revealed by scanning electron microscopy. For the oxidation of carbon monoxide, propane or methane diffusion limitation can be substantial at typical operating conditions. The two‐dimensional solution is compared to a one‐dimensional approximation. The latter approximation for the real washcoat is valid provided that the characteristic length is selected carefully. This value is different from the characteristic length of the two‐dimensional washcoat. The characteristic length of a two‐dimensional geometry is not sufficient in itself to describe all washcoat geometries. It is predicted that the application of a diffusion barrier of 4–6 μm of inactive washcoat may be used to lower the rate of reaction in the inlet region of the monolith reactor.