Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 78: Poster: Surface Dynamics - Reactions, Elementary Processes and Phase Transitions
O 78.12: Poster
Mittwoch, 14. März 2018, 18:15–20:30, Poster A
Reactivity of benzene on a sulfur-passivated Pt(111) surface — Johann Steinhauer, Philipp Bachmann, Udo Bauer, Florian Späth, Fabian Düll, Hans-Peter Steinrück, and •Christian Papp — Lehrstuhl für Physikalische Chemie II, FAU Erlangen-Nürnberg, Egerlandstr.3, 91058 Erlangen, Germany
Poisoning of catalysts with sulfur is a major issue in large scale applications. One very efficient poison for catalysts is sulfur, which leads to the blocking of reactive sites and a strong reduction of the total adsorption capacity. Interestingly sulfur is also used as a promoter in the dehydrogenation reaction of hydrocarbons. To understand the particular influence of sulfur in this reaction, we studied the effect of sulfur contamination on the reaction behavior of benzene on a Pt(111) single crystal with Temperature Programmed Desorption (TPD) and synchrotron based high-resolution XPS. In these studies, the sulfur coverages were varied up to 0.3 ML, obtained by adsorbing H2S and subsequent annealing to 500 K. We followed the reaction of benzene on Pt(111) as a function of sulfur coverage. For sulfur-poisoned surfaces we find the desorption of benzene occurs at slightly lower temperatures of about 400 K. On the sulfur free Pt(111) surface also the reaction and decomposition is found at higher temperatures of 435 and 640 K, respectively. This effect of sulfur on the reaction was also found in TPD measurements. Sulfur leads to a shift of the desorption peaks to lower temperatures with increasing sulfur coverages. Thereby indicating a decreased binding energy between catalyst and substrate or a deactivation of active sites on the catalyst through sulfur poisoning.