Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 73: Poster Metal and Semiconductor Substrates: Adsorption and Reactions of Small Molecules

O 73.4: Poster

Mittwoch, 19. März 2025, 18:00–20:00, P2

An XPS and molecular beam study of olefin adsorption on ultrathin ionic liquid films on Pt(111) — •Laura Ulm, Cynthia C. Fernández, Leonhard Winter, Florian Maier, and Hans-Peter Steinrück — Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg

Solid catalysts with ionic liquid layer (SCILL) promise improvements for a wide range of applications, e.g. an enhanced selectivity of the 1,3-butadiene hydrogenation to 1-butene by coating a heterogeneous catalyst with thin ionic liquid (IL) films. We studied hydrocarbon adsorption as central step of this reaction by X-ray photoelectron spectroscopy combined with a supersonic molecular beam. Ultrathin films of three different ionic liquids with thicknesses below 1 nm were deposited onto a Pt(111) crystal in UHV by physical vapor deposition and characterized with XPS. These films were exposed to 1,3-butadiene or 1-butene from a supersonic molecular beam at 180 K. The coverage-dependent sticking coefficients of the two olefins were measured using the King-and-Wells method. With increasing IL pre-coverage, the total amounts of adsorbed olefins decreased until further adsorption was completely suppressed by the IL layer. The minimum IL coverage needed for complete suppression of adsorption and the differences between the ionic liquids will be discussed in the context of IL-induced selective 1,3-butadiene hydrogenation.

Supported by the DFG through SFB 1452 (Project ID: 431791331).

Keywords: Ionic Liquid; SCILL; XPS; Molecular Beam; Adsorption