Steady state methane partial oxidation has been examined around the syngas stoichiometry as a function of preheat on rhodium coated alumina monoliths. The results of these experiments show very interesting structure within the catalyst. First there is an oxidation zone lasting 2-3 mm in which all oxygen is consumed and a considerable amount of syngas is produced. Next there is a reforming zone in which water and methane are consumed giving H2 and CO in the approximate methane steam reforming stoichiometry. A peak in temperature is generally observed in the middle of the catalyst towards the beginning of the reforming zone indicating the beginning of endothermic chemistry in the catalyst. Surprisingly there is additional fine structure in the profiles of washcoated Rh catalysts indicating that there is a methanation zone within the catalyst. In the methanation zone there is a net consumption of H2 and CO giving a small peak in methane. After the small peak in methane it is steam reformed again giving H2 and CO.
This novel method for collecting species and temperature can be used to gather a large amount of data within the catalyst for steady state experiments (e.g. for methane and other fuels) which will be very useful for validating and updating existing reaction mechanisms. Because of the fast response of the data collection scheme, this experimental system also lends itself to the analysis of transient experiments which can be even more powerful for validating reaction mechanisms and carbon coverages within the catalyst.