Study of CO adsorption on crystalline-silica-supported palladium particles

Supported palladium particles have been studied using a recently developed crystalline silica film. The SiO2 film, as seen for the first time by scanning tunnelling microscopy (STM), is sufficiently flat to be used for model catalyst studies. Palladium particles grown on silica at room temperature are round and somewhat disordered as seen by STM, suggesting a strong interaction between the Pd particles and the silica support, The structural properties of the palladium particles were probed by CO adsorption at 90 K. and monitored by IRAS. The same general adsorption sites are observed for the Pd particles grown on silica as have previously been observed for crystalline Pd particles on alumina, however a larger fraction of on-top sites was observed on silica, indicative of the smaller and more disordered particles. These first results obtained for the Pd/SiO2/Mo(112) system are encouraging for the use of the crystalline SiO2 substrate as a model-catalyst support. (C) 2001 Published by Elsevier Science B.V.