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Abstract

MCM 41 was loaded with ligand-stabilized palladium clusters in the size range of 3-4 nm via different pathways. A mixture of seven- and eight-shell clusters (Pd7/8(phen)) was directly introduced into the mesoporous structure during the synthesis of MCM 41 as well by incipient wetness impregnation. The Samples were characterized by X-ray diffraction, N²-sorption, DTA and TEM. The clusters show different thermal stability depending on the synthesis pathway used. In situ incorporation leads to a decomposition of the Pd clusters after calcination at 873 K. However, the clusters that were introduced by incipient wetness impregnation are thermally stable up to 513 K in air. As a first catalytic test the oxidation of CO with synthetic air was used. Compared to catalysts prepared by conventional methods with appropriate palladium salts, the impregnated samples show high activity in the CO oxidation.