Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 16: Nanoscale Heterogeneous Catalysis
O 16.4: Talk
Monday, March 16, 2020, 16:00–16:15, TRE Ma
Palladium nanoparticles supported on sapphire (0001): Decomposition of metastable palladium carbide under LOHC and under inert gas atmosphere — •Ralf Schuster1, Manon Bertram1, Henning Runge2, Simon Chung2, Vedran Vonk2, Heshmat Noei2, Yaroslava Lykhach1, Andreas Stierle2, and Jörg Libuda1 — 1Interface Research and Catalysis, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058 Erlangen — 2Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, D-22607 Hamburg
Surface carbon species can be formed by unselective decomposition during heterogeneously catalyzed dehydrogenation of liquid organic hydrogen carriers (LOHCs). These species may diffuse into the bulk of the catalyst, forming a metal carbide phase. For palladium, however, the carbide phase is metastable with respect to palladium and graphite. Therefore, we studied the stability of palladium carbide on sapphire-supported Pd nanoparticle model catalysts. Two different particle sizes were investigated under reaction conditions (500 K, 1 bar) by high-energy grazing incidence X-ray diffraction. For small particles and low gas flow rate, the carbide formed is stable in LOHC atmosphere but decomposes under pure argon. Increasing the gas flow rate results in immediate decomposition of the carbide even in the presence of LOHC. Studies on bigger particles at low gas flow rate show a different behavior. Here, the carbide is stable in the presence of LOHC only for a limited amount of time before it decomposes in further contact with the LOHC.