ACS Publications
The composition of reaction mixtures strongly influences the structural evolution and performance of noble metal-based catalysts. In this work, we compared the effect of the simultaneous presence of CO and NO on the noble metal state and CO oxidation activity of Pt/Al2O3 and Pt/CeO2 catalysts under close-to-stoichiometric conditions using complementary in situ/operando X-ray and infrared spectroscopic techniques. For the utilized catalysts, the integral catalytic performance data indicated a diminished CO oxidation activity in the presence of NO, which is due to a competitive adsorption of CO and NO, as elucidated by the diffuse reflectance infrared Fourier transform spectroscopy and high-energy resolution X-ray fluorescence X-ray absorption near-edge structure results. Spatially resolved operando X-ray absorption spectroscopy investigations and extended X-ray absorption fine structure analysis unraveled that the addition of NO led to a higher oxidation state of Pt along the entire catalyst bed for both samples. Moreover, NO was found to delay the reduction of Pt particles on Al2O3 and hinder the formation of active Pt clusters on CeO2. As a result, a more oxidized Pt state at the beginning of the catalyst bed and a low overall activity were observed for Pt/CeO2. However, the CO oxidation activity could be enhanced by a reductive pretreatment of the Pt/CeO2 catalyst, resulting in a similar reduced Pt state along the entire catalyst bed and minimizing the negative impact of NO during the combined reaction.
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Complementary and Spatially Resolved Operando Spectroscopic Investigation of Pt/Al₂O₃ and Pt/CeO₂ Catalysts during CO/NO Conversion
Jan-Dierk Grunwaldt 1, Daria Gashnikova 2, Samuel Struzek 2, Florian Maurer 2, Miriam R. Bauer 2, Carina B. Maliakkal 3, Christian Kübel 4, Maria Casapu 2,
1) Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), Engesserstrasse 18, 76131 Karlsruhe, Germany; Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany;
2) Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), Engesserstrasse 18, 76131 Karlsruhe, Germany;
3) Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
4) Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany; Department of Materials and Earth Sciences, Technical University Darmstadt (TUDa), Peter-Grünberg-Straße 2, 64287 Darmstadt, Germany;
DOI: https://pubs.acs.org/doi/full/10.1021/acs.jpcc.5c01963
