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O: Oberflächenphysik
O 18: Adsorption an Oberfl
ächen II
O 18.6: Talk
Saturday, March 5, 2005, 12:00–12:15, TU EB301
PM-IRAS and XPS studies of methanol oxidation on Pd model catalysts — •Marta Borasio, Oscar Rodríguez de la Fuente, Günther Rupprechter, and Hans-Joachim Freund — Fritz-Haber-Institut, Faradayweg 4-6, 14195 Berlin
Methanol decomposition and oxidation on Pd(111) and Al2O3 supported Pd nanoparticles were studied by Polarization-Modulation Infrared Reflection Absorption Spectroscopy (PM-IRAS) and X-ray Photoelectron Spectroscopy (XPS) from ultrahigh vacuum (UHV) to 15 mbar, at temperatures up to 450 K. Under high pressure these processes were also followed by gas chromatography (GC).
Methanol decomposition proceeds via dehydrogenation to CO and hydrogen or via methanolic C-O bond scission producing carbonaceous species (CHx or C), which deactivate the catalyst. The kinetics of the evolution of these species and their preferred binding sites were analyzed. During methanol oxidation at mbar pressure surface species (CO, CHxO) and products (CO2, H2O, CH2O) were detected by PM-IRAS and GC, respectively, with XPS being utilized for pre- and post-reaction surface analysis.