Analysing the Reaction Kinetics for Individual Catalytically Active Components: CO Oxidation on a Pd Powder Supported by Pt Foil

Spatially- and component-resolved kinetic measurements and resulting phase diagrams for CO oxidation on a model catalyst consisting of Pd powder agglomerates supported by a polycrystalline Pt foil are reported. The kinetic data for the micrometer-sized Pt(100) and Pt(110) domains and for the different Pd powder agglomerates of similar dimensions were obtained by local analysis of PEEM video-sequences recorded in situ during the ongoing CO oxidation reaction. Individual domains of the supporting Pt foil as well as the A mu m-sized Pd powder agglomerates behave in the combined Pd-powder/Pt-foil sample independently from each other with respect to CO oxidation, at least in the 10(-5) mbar pressure range. The propagating reaction fronts move within grain boundaries for Pt domains and also remain confined to the Pd agglomerates. [GRAPHICS] .