Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 40: Heterogeneous Catalysis: Experiment
O 40.2: Vortrag
Dienstag, 8. März 2016, 14:15–14:30, S053
Physical and chemical properties of Au nanoparticles on CeO2 supports in the CO oxidation reaction — •Joachim Bansmann1, Gabriela Kucerova1, Ayman Abd El-Moemen2, Ali Abdel-Mageed1, and R. Jürgen Behm1 — 1Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany — 2Chemistry Department, Suez Canal University, Ismailia, Egypt
Au nanoparticles (NPs) on metal oxide surfaces are interesting catalysts in the CO oxidation and water-gas shift (WGS) reaction. Here, we will focus on the influence of different oxidic and reductive pre-treatments of Au/CeO2 catalysts on the size and the oxidation state of the Au NPs using ex-situ characterization techniques (XRD and XPS) as well as in-situ methods such as XANES/EXAFS and diffuse IR spectroscopy (DRIFTS). Reductive pre-treatments in CO generally lead to smaller metallic particles, whereas the presence of oxidic species results in slightly larger and partially oxidic Au NPs.
Moreover, using these in-situ spectroscopy techniques, we followed the changes in the Au particle size and chemical state in the CO oxidation reaction after the different pre-treatments. Sintering/Ostwald ripening process affect the catalytic activity by lowering the surface area of Au which contributes to a decreasing reactivity. Additionally, DRIFTS measurements offer insight into adsorption sites of CO on Au NPs and the formation of carbonates and formates, which often block active site in the CO oxidation reaction.