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O: Oberflächenphysik

O 46: Adsorption an Oberfl
ächen V

O 46.8: Vortrag

Dienstag, 8. März 2005, 17:30–17:45, TU EB420

A comparative study of prenal on Pt(111), Pt₂Sn(111) and Pt₃Sn(111) surface alloys — •Jan Haubrich, Alexander Krupski, Conrad Becker und Klaus Wandelt — Inst. f. Phys. u. Theo. Ch., Wegeler. 12, D-53115 Bonn

It is known that the selectivity of the hydrogenation processes of α,β-unsat. aldehydes like acrolein or prenal depends not only on the molecule itself, but also on the catalyst employed. To understand the different selectivities, the adsorption of prenal on Pt(111) and two Pt-Sn surface alloys is investigated with HREELS, TPD and LEED.

After adsorption of prenal at 100K the desorption of fragments up to 100 amu is studied with TPD. While on Pt(111) the desorption of prenal is detected at 160K (Multilayer), 177K and 199K, also a fragmentation reaction is observed giving rise to desorption of H₂ and CO in several peaks. On Pt₂Sn and Pt₃Sn surface alloys this fragmentation process is suppressed. HREELS experiments carried out between 100K and 500K on the three surfaces show highly complex spectra of adsorbed prenal. On Pt(111) also the fragmentation process starting at 300K can be examined with HREELS. Also on the Pt_xSn surfaces complex HREEL spectra of prenal are recorded.