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O: Fachverband Oberflächenphysik

O 49: Surface chemical reactions I

O 49.9: Vortrag

Mittwoch, 24. März 2010, 12:30–12:45, H42

Adsorption and reaction of SO₂ on clean and oxygen precovered Pt surfaces — •Regine Streber¹, Christian Papp¹, Michael Peter Andreas Lorenz¹, Andreas Bayer¹, Oliver Höfert¹, Wei Zhao¹, Sandra Wickert², Erik Darlatt², Reinhard Denecke², and Hans-Peter Steinrück¹ — ¹Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen — ²Willhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstr. 2, 04103 Leipzig

Sulfur and its oxides are well-known poisons in large scale applications of heterogeneously catalyzed reactions. We studied the adsorption and thermal evolution of SO₂ on clean and oxygen precovered Pt surfaces by in-situ high-resolution XPS applying synchrotron radiation at BESSY II. The comparison of spectra obtained on flat and stepped Platinum allows to elucidate the role of steps for the thermal stability of different SO₂ species, and in particular for their disproportionation to S and SO₃ upon heating. On the oxygen precovered surfaces a fraction of SO₂ reacts to SO₃ immediately upon adsorption, even at temperatures as low as 100 K. Heating of the resulting mixed adsorbate layers first results in the reaction of all remaining SO₂ species to SO₃, followed by subsequent oxidation to SO₄ above 300 K.