The objective of this investigation is a better understanding of transient processes in catalytic monoliths. As an example, the light-o( of
the partial oxidation of methane to synthesis gas (H2 and CO) on a rhodium/alumina catalyst is studied experimentally and numerically.
Methane/oxygen/argon mixtures are fed at room temperature and atmospheric pressure into a honeycomb monolith, which is preheated
until ignition occurs. The exit gas-phase temperature and species concentrations are monitored by a thermocouple and mass spectroscopy,
respectively. In the numerical study, the time-dependent temperature distribution of the entire solid monolith structure and the
two-dimensional laminar reactive 2ow 3elds in the single monolith channels are simulated. A multi-stepheterogeneous reaction mechanism
is used, and the surface coverage with adsorbed species is calculated as function of the position in the monolith. During light-o(, complete
oxidation of methane to water and carbon dioxide occurs initially. Then, synthesis gas selectivity slowly increases with rising temperature.
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