  In this paper, the pore network model to investigate the reaction-diffusion
process in the hierarchically structured porous catalyst particle is extended
to consider the phenomenon of deactivation by coking. In this framework, the
interaction of internal particle pore structure and mass transfer under the
condition of coke deposition are examined. A primitive experimental
investigation has been performed as an introduction to the development of the
model. Then, the effect of structural features namely macroporosity and pore
size ratio, the deactivation properties, the maximum loading of coke as well as
the transport properties, the pore Damkohler number on the net reaction rate
and deactivation of the particle have been investigated. Three deactivation
mechanisms are accounted for, namely, the site coverage, the pore narrowing,
and the pore blockage. It is found that the deactivation of the catalyst
particle can be divided into two conditions: the kineticsal deactivation and
the structural deactivation. It is shown that depending on the Damkohler
number, increasing the macroporosity does not necessarily improve the
reactivity and deactivation resistance of the catalyst. The key finding of this
work is to demonstrate and quantify how changing the typical fresh catalyst
microstructure observed in the experimental characterization into a
hierarchical one influences the reactivity and deactivation.
