AVS 47th International Symposium
    Surface Science Monday Sessions
       Session SS1-MoM

Paper SS1-MoM7
Adsorption and Reaction on Oxide-supported Pd, Rh and Ir Particles

Monday, October 2, 2000, 10:20 am, Room 208

Session: Atomic-Scale Studies of Model Catalysts
Presenter: M. Baeumer, Fritz-Haber-Institut, Germany
Authors: M. Baeumer, Fritz-Haber-Institut, Germany
M. Frank, Fritz-Haber-Institut, Germany
S. Shaikhutdinov, Fritz-Haber-Institut, Germany
H.-J. Freund, Fritz-Haber-Institut, Germany
Correspondent: Click to Email
Supported metal clusters and nanoparticles are of fundamental and technical interest. One important area of application is heterogeneous catalysis, for example. On a microscopic level, however, there is only limited knowledge about the dependence of adsorption behaviour and catalytic activity on particle size and morphology. In order to contribute to an understanding of these relationships, we have studied oxide-supported Pd, Rh and Ir particles and their interaction with adsorbates. As a support, a thin alumina film grown on NiAl(110) was employed so that scanning tunneling microscopy and electron spectroscopies could be applied without charging problems. The STM results show that particle sizes ranging from a few atoms up to several thousand atoms are accessible via growth under vacuum conditions. By changing the temperature during deposition, disordered as well as crystalline aggregates are obtainable. After having dealt with the structure, we discuss the adsorption and reaction of ethene on these systems. The studies, which have been carried out using infrared and photoelectron spectroscopy, shed light on the formation of differently co-ordinated species and their thermal dehydrogenation. Gradual changes depending on the metal and the particle size are observed. Finally, we turn to the hydrogenation of ethene with hydrogen which has been investigated by thermal desorption spectroscopy.