Interaction of NO2 with Model NSR Catalysts: Metal-Oxide Interaction Controls Initial NOx Storage Mechanism

• Published in: Chemphyschem 2008-10, Vol.9 (15), p.2191-2197
• Main Authors: Desikusumastuti, Aine, Staudt, Thorsten, Qin, Zhihui, Happel, Markus, Laurin , Mathias, Lykhach, Yaroslava, Shaikhutdinov, Shamil, Rohr, Friedemann, Libuda, Jörg
• Format: Article
• Language: English
• Subjects: Catalysis; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; heterogeneous catalysis; IR spectroscopy; model catalysts; molecular beams; Physical and chemical studies. Granulometry. Electrokinetic phenomena; reaction mechanisms; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.200800550

Using scanning tunneling microscopy (STM), molecular‐beam (MB) methods and time‐resolved infrared reflection absorption spectroscopy (TR‐IRAS), we investigate the mechanism of initial NOx uptake on a model nitrogen storage and reduction (NSR) catalyst. The model system is prepared by co‐deposition of Pd metal particles and Ba‐containing oxide particles onto an ordered alumina film on NiAl(110). We show that the metal–oxide interaction between the active noble metal particles and the NOx storage compound in NSR model catalysts plays an important role in the reaction mechanism. We suggest that strong interaction facilitates reverse spillover of activated oxygen species from the NOx storage compound to the metal. This process leads to partial oxidation of the metal nanoparticles and simultaneous stabilization of the surface nitrite intermediate. Model catalyst: Nitrite formation during the initial stages of NOx uptake on a nitrogen storage and reduction (NSR) catalyst is critically controlled by the interaction between the barium based NOx storage material and the supported noble metal nanoparticles. This effect is due to reverse spillover of activated oxygen species, as demonstrated by experiments on a NSR model catalyst.