Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 67: Gerhard Ertl Young Investigator Award (talks of the selected canditates)

O 67.3: Vortrag

Donnerstag, 25. März 2010, 11:30–12:00, H37

Probing the surface state and reactivity of an active catalytic site: from single-site catalysts to nanoparticles — •Elena Groppo — Department of Inorganic, Physical and Material Chemistry, NIS Centre of Excellence and INSTM Unità di Torino, University of Torino

The utility of applying advanced spectroscopic techniques in determining the properties of the active catalytic sites, the difficulties encountered and the possible strategies to overcome the problems, will be discussed in this contribution by considering two case studies, which are among the simplest examples of single-site and multiple-site catalysts, respectively:

(i) the CrII/SiO2 system, which catalyses the ethylene polymerization. Interaction with CO was studied since decades by in situ FT-IR spectroscopy and more recently by Raman spectroscopy, both giving a clear, although indirect, proof that an important rearrangement of the local environment of the CrII site at the silica surface occurs upon CO adsorption. Very recently, XAS experiments offer the first direct experimental evidence of adsorption induced mobility of CrII sites, which is the key for understanding the catalytic activity of CrII sites in presence of adsorbates.

(ii) supported Pd nanoparticles, which catalyse hydrogenation reactions. EXAFS, UV-Vis and FT-IR spectroscopies, coupled with TEM microscopy, are used to investigate the structural, optical and vibrational properties of two Pd/polymer systems in all the synthetic steps, starting from the hosted Pd(OAc)2 precursors up to Pd nanoparticles.