The elucidation of the size/composition/shape/structure and function correlation is instrumental for the design of new catalysts. Uniform particles are prerequisites for such studies, making size-selected clusters of few atoms to several nm in size as ideal model systems. The experiments are based on 1) size-selected cluster deposition, 2) electron microscopy and 3) in situ synchrotron X-ray characterization under working conditions (scattering and absorption), combined with 4) mass spectroscopy of products. DFT calculations performed by our collaborators are instrumental at the understanding of the catalytic properties of these materials. In this presentation, examples will be given on bridging the size gap between the sub-nanometer and nanometer cluster size regime and on coupling studies of model size-selected [1-3] and "real"- with wet chemical methods prepared [4-6] catalysts. Processes discussed will include dehydrogenation, Fischer-Tropsch synthesis and partial oxidation of alkenes. For example, our studies led to the identification of a new class of silver-based direct propylene epoxidation catalyst which works at considerably lower temperatures than existing ones [1]. The role of the size in catalyst's activity and the evolving morphology of silver nanoclusters under epoxidation conditions will be addressed [1-3], followed by the discussion of strong size, composition and support effects in dehydrogenation [4,5], hydrogenation [6] and Fischer–Tropsch reactions.

  

[1] Y. Lei, F. Mehmood, S. Lee, J. P. Greeley, B. Lee, S. Seifert, R. E. Winans, J. W. Elam, R. J. Meyer, P. C. Redfern, D. Teschner, R. Schlögl, M. J. Pellin, L. C. Curtiss, and S. Vajda, Science 328, 224 (2010)

[2] S. Vajda, S. Lee, K. Sell, I. Barke, A. Kleibert, V. von Oeynhausen, K.-H. Meiwes-Broer, A. Fraile-Rodriguez, J. W. Elam, M. J. Pellin, B. Lee, S. Seifert, R. E. Winans , J. Chem. Phys., 131, 121104 (2009),

[3] L. M. Molina, S. Lee, K. Sell, G. Barcaro, A. Fortunelli, B. Lee, S. Seifert, R. E. Winans, J. W. Elam, M. J. Pellin, I. Barke, A. Kleibert, V. von Oeynhausen, Y. Lei, R. J. Meyer, J. A. Alonso, A. Fraile-Rodríguez, S. Giorgio, C. R. Henry, K.-H. Meiwes-Broer, and S. Vajda, Catal. Today, invited, under review

[4] M. Di Vece, S. Lee, X. Wang, B. Lee, S. Seifert, R.E. Winans, M. Neurock, G. Haller, L. D. Pfefferle, and S. Vajda, in preparation

[5] M. Di Vece, S. Lee, R. Si, B. Ricks, S. Seifert, R.E. Winans, M. Flytzani-Stephanopoulos, and S. Vajda, in preparation

[6] S. A. Wyrzgol, S. Schäfer, S. Lee, B. Lee, M. Di Vece, X. Li, S. Seifert, R. E. Winans, M. Stutzmann, J. A. Lercher, and S. Vajda, 2010, Phys. Chem. Chem. Phys. feature article, on-line April 27, 2010