Towards a better understanding of transient processes in catalytic oxidation reactors

Light-off of the partial oxidation of methane to synthesis gas on a rhodiumcoated cordierite honeycomb monolith at short contact times is studied experimentally and numerically. The objective of this investigation is a better understanding of transient processes in catalytic oxidation reactors. The numerical simulation predicts the time-dependent solid-temperature distribution of the entire reactor and the two-dimensional flow fields, species concentrations, and gas-phase temperature profiles in the single channels. A detailed reaction mechanism is applied, and the surface coverage with adsorbed species is calculated as function of the position in the monolith. During light-off, complete oxidation of methane to water and carbon dioxide occurs initially. Then, synthesis gas selectivity slowly increases with rising temperature. The numerically predicted exit temperature, conversion, and selectivity agree well with the experimentally derived data.