Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)
O 60.108: Poster
Mittwoch, 16. März 2011, 17:30–21:00, P4
Spectroscopic Identification of initial decomposition mechanism of Prenal on a Platinum Model Catalyst — •Jan Haubrich1, David Loffreda2, Francoise Delbecq2, Philippe Sautet2, Yvette Jugnet3, Conrad Becker4, and Klaus Wandelt1 — 1Inst. für Phys. und Theo. Chemie, Uni. Bonn — 2Lab. de Chimie, Ecole Normale Supérieure de Lyon — 3Inst. de Rech. sur la Catalyse, Villeurbanne — 4CINAM, Aix-Marseille Uni.
The prediction of reaction mechanisms consisting of complex networks of elementary steps and the identification of corresponding intermediates are major challenges in multifunctional catalysis and surface chemistry. We demonstrate that this difficulty can be overcome by tracking the temperature dependent formation of the intermediates and identifying the decomposition pathways in the case prenal, an α,β-unsaturated aldehyde, on the Pt(111) model catalyst surface by combining vibrational spectroscopy, temperature-programmed reaction spectroscopy and DFT analysis. Desorption states of H2 (280 K, 410 K and 473 K) and CO (414 K) suggest that the loss of H and the CO functions are among the first elementary steps. HREELS performed after annealing to specific temperatures results in spectra which can be assigned to several subsequently formed surface intermediates with the help of complementary theoretical vibrational analysis. The most likely reaction pathway obtained from DFT for intial decomposition occurs from the strongly bonded prenal adsorption structures via an dehydro-η3-triσ(CCC)-H1 intermediate to the η1-isobutylidyne species at high temperatures.