Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 31: Oberflächenreaktionen II

O 31.7: Vortrag

Donnerstag, 11. März 2004, 12:45–13:00, H36

SFG and TDS studies of methanol adsorption and decomposition on Pd model catalysts — •Matthias Morkel, Günther Rupprechter und Hans-Joachim Freund — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Abt. Chemische Physik, Faradayweg 4-6, 14195 Berlin

Methanol adsorption and decomposition on Pd(111) and Al2O3-supported Pd-nanoparticles were studied by sum frequency generation (SFG) vibrational spectroscopy from ultrahigh vacuum (UHV) to 100 mbar, at temperatures up to 400 K. Under UHV, these processes were also followed by thermal desorption spectroscopy (TDS).

The decomposition of methanol can be seperated in two reaction pathways. A fast reaction pathway leads to formation of CO and hydrogen. The second pathway produces carboneacious species (CHx or C) by scission of the CO-bond of methanol. Although the reaction rate of the latter pathway is much lower, it cannot be negelected under high-pressure. Depending on the temperature the carbon poisoning leads to a partial or complete deactivation of the catalyst. The binding sites of the carbon species were characterized by SFG using CO as probe molecule. Regeneration with oxygen was able to (partly) remove the carbon deposits.

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