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O: Fachverband Oberflächenphysik

O 11: Surface Reactions

O 11.2: Vortrag

Montag, 27. März 2023, 15:15–15:30, CHE 91

The effect of ultrathin ionic liquid films on the adsorption dynamics of 1,3-butadiene and 1-butene on Pt(111) studied by molecular beam techniques — •Leonhard Winter, Cynthia Carolina Fernández, Afra Gezmis, Timo Talwar, Stephen Massicot, Florian Maier, and Hans-Peter Steinrück — Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen

Ionic Liquids (ILs) are low temperature melting salts. In “Solid Catalyst with Ionic Liquid Layer (SCILL)” systems, IL thin films are used to coat the catalytically active metal and thereby enhance the selectivity of the catalyst; this approach is beneficial, e.g., in the industrially important hydrogenation of 1,3-butadiene to butenes, since further hydrogenation to n-butane must be suppressed. We used a supersonic molecular beam to investigate the adsorption dynamics of this reaction in a UHV SCILL model system. Along the method of King and Wells we measured sticking coefficients of 1,3-butadiene and 1-butene on Pt(111) coated with ultrathin layers of the IL 1,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C1C1Im][Tf2N]). At 180 K, the sticking coefficients decrease non-linearly with increasing IL coverage. We explain the deviation from a simple site-blocking model with trapping into a mobile precursor state of the hydrocarbon molecules that arrive on top of IL islands. This deviation is less pronounced for films prepared at 250 K, which we attribute to larger IL island sizes.

Supported by the DFG through SFB 1452 CLINT.