Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 93: Surface Chemical Reactions
O 93.4: Talk
Friday, February 29, 2008, 11:00–11:15, MA 043
Modeling NOx Storage Materials: Adsorption and interaction of NO2 with BaO nanoparticles — •Thorsten Staudt1, Aine Desikusumastuti1, Sandra Gardonio2, Silvano Lizzit2, Erik Vesselli3, Alessandro Baraldi3, and Jörg Libuda1 — 1Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen, Germany — 2Sincrotrone Trieste, Italy — 3Physics Department, University of Trieste, Italy
In order to obtain a fundamental understanding of the underlying processes of NOx storage and reduction (NSR) catalysts we have studied the reaction of NO2 with BaO nanoparticles supported on an ordered Al2O3 thin film on NiAl(110).
We use a combination of high-resolution XPS obtained at the synchrotron radiation facility ELETTRA in Triest, vibrational spectroscopy (IRAS) and molecular beam (MB) techniques. Various nitrogen-oxo surface intermediates are identified by XPS and IRAS and the reaction behaviour shows a strong temperature dependence. At 300 K surface nitrites are formed and the conversion into surface nitrates occurs only at a very low rate. These reactions are only limited to the surface of the BaO particles. At 500 K the conversion into nitrates is more facile and nitrate formation proceeds beyond the particle surface, which yields to the formation of ionic nitrates.
Decomposition experiments exhibit that the stability of the barium nitrate nanoparticles is strongly depended on the particle size [1]. The larger particles are stable up to a temperature of 650 K, whereas the surface related species on small particles decompose at a temperature of 350-450 K.
[1] A. Desikusumastuti et al., Catal. Lett., in press