[Zurück]

M. Datler, I. Bespalov, G. Rupprechter, Y. Suchorski:
"Spatially- and component-resolved reaction kinetics on a µm-scale: CO oxidation on Pd model catalysts";
Poster: ECOSS-31 31st European Conference on Surface Science, Barcelona; 31.08.2015 - 04.09.2015; in: "Book of Abstracts", (2015), S. 577.

Most of the practically useful catalysts are complicated heterogeneous systems exhibiting strong local variations of catalytic activity. Since theoretical calculations cannot yet provide reliable predictions for the local reaction kinetics even on the mesoscopic (mkm) scale, the problem of laterally-resolved studies of reaction kinetics is still up-to-date. Recently, it was demonstrated that information about local reaction kinetics for individual mkm-sized grains of a polycrystalline Pt foil can be obtained "just by imaging" using PEEM [1, 2]. We extend herewith this approach to model catalysts consisting of Pd powder supported by metal and oxidic supports. The kinetic data for the individual µmsized Pd powder agglomerates were obtained by digital analysis of PEEM video-sequences recorded in situ during the ongoing CO oxidation reaction. From the same video-sequences, the data for the individual (100) and (110) domains of the supporting Pt foil were obtained. The Pd powder agglomerates and the supporting Pt domains behave in the combined Pdpowder/Ptfoil sample independently from each other with respect to the 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. Substituting the supporting Pt foil by oxidic support allows allows to elucidate the effect of the support via comparison of the catalytic behaviour of individual metal- and oxide-supported Pd powder agglomerates.

[1] Y. Suchorski, C. Spiel, D. Vogel, W. Drachsel, R. Schlögl, G. Rupprechter, Chem.Phys.Chem. 11 (2010) 3231. [2] D. Vogel, Ch. Spiel, A. Suchorski, A. Trinchero, R. Schlögl, H. Grönbeck and G. Rupprechter Angew. Chem. Int. Ed. 51 (2012) 10041.