(24g) Interstitial-Scale Modeling of Catalytic Foam Reactors: Partial Oxidation of Methane | AIChE

(24g) Interstitial-Scale Modeling of Catalytic Foam Reactors: Partial Oxidation of Methane

Authors 

Wehinger, G. D. - Presenter, Technische Universität Berlin
Kraume, M. - Presenter, Technical University Berlin

Interstitial-scale modeling of catalytic foam reactors: partial oxidation
of methane

Gregor
Wehinger, Matthias Kraume

Chemical
and Process Engineering, Technische Universität Berlin, Fraunhoferstr. 33-36,
10587 Berlin, Germany

Catalytic foams represent
a promising alternative to conventional fixed-bed reactors in many
applications in the chemical and process industry. They are characterized by
their low specific pressure drop, high mechanical stability at relatively
low specific weight, enhanced radial transport, as well as a high
geometric surface area. Designing and planning of foam reactors can be
supported by computational fluid dynamics (CFD) simulations. However, the
actual shape of a catalytic foam is highly complex and therefore difficult to
model.

In this work we present a
fully automatic workflow (catalytic Foam Modeler: catFM) with which it is
possible to model a realistic foam structure ready for CFD simulations without
using data from time consuming image analysis. The modeler is based on a random
distribution of points in space followed by the Voronoi tessellations. It
applies common foam characteristics, i.e., porosity, specific surface
area and strut dimensions, as input parameters to generate artificially
the foam structure. Typical morphological parameters such as specific
surface area, as well as pressure drop predictions can be reproduced with a
high accuracy. Finally, the performance of the tool catFM is illustrated by
modeling a catalytic partial oxidation reformer of methane in a foam coated
with a rhodium catalyst from literature [1]. Two sets of simulations are
performed, one with a fixed surface temperature profile obtained from
experiment, the other takes heat transfer inside the solid material into
account. On the surface a detailed reaction mechanism is implemented [2]. For
both cases, the experimental species profiles can be well reproduced.
However, only the second set allows a flexible utilization without
knowing the temperature profile a priori. With this modeler it is
possible to plan and design catalytic foams by predicting temperature and
species concentrations without relying on transport correlations.


Fig 1: CFD setup for foam simulations with details of strut geometry and
mesh resolution close to surface.

[1] Nogare, D. D.;
Degenstein, N.; Horn, R.; Canu, P. & Schmidt, L. Modeling spatially
resolved profiles of methane partial oxidation on a Rh foam catalyst with
detailed chemistry, Journal of Catalysis , 2008,
258
, 131 - 142

[2] Schwiedernoch, R.; Tischer, S.; Correa, C. &
Deutschmann, O. Experimental and numerical study on the transient behavior of
partial oxidation of methane in a catalytic monolith, Chemical
Engineering Science, 2003, 58
, 633 - 642