Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 82: Fundamentals of Catalysis II
O 82.3: Vortrag
Donnerstag, 4. April 2019, 15:30–15:45, H5
Dehydrogenation of Liquid Organic Hydrogen Carriers on Supported Pd Model Catalysts: Carbon Incorporation under Operation Conditions — •Ralf Schuster1, Fabian Waidhas1, Manon Bertram1, Henning Runge2, Simon Geile2, Simon Chung2, Vedran Vonk2, Heshmat Noei2, Yaroslava Lykach1, Florian Bertram2, Andreas Stierle2, and Jörg Libuda1 — 1Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058 Erlangen — 2Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, D-22607 Hamburg
Hydrogen and carbon, formed during the dehydrogenation and unselective decomposition of liquid organic hydrogen carriers (LOHCs) under reaction conditions, may diffuse into the bulk of the catalyst and, thus, change its activity and selectivity. We studied the influence of hydrogen and carbon on a sapphire-supported Pd nanoparticle (NP) model catalyst under reaction conditions (500 K, 1 bar) by high-energy grazing incidence X-ray diffraction. In pure H2 at 300 K, the Pd NPs show a continuous transition from the α-PdH to β-PdH phase with increasing H2 partial pressures, while the miscibility gap is narrowed in comparison to bulk Pd. With increasing temperature, the hydrogen uptake decreases and at 500 K, no hydride phase is formed. Surface carbon, formed by decomposition of the LOHC at 500 K, diffuses into the NP bulk. Our studies show that this formation of bulk carbon is efficiently suppressed in the presence of H2. This highlights the importance of controlling the partial pressure of H2 during dehydrogenation of LOHCs over Pd-based catalysts in real hydrogen release units.