X-ray photoelectron spectroscopy is used to study the interaction of model NO 2 storage-reduction catalysts (NSR catalysts) Ba/TiO 2 and Ba/ZrO 2 with NO 2. The catalysts are prepared on the surface of ultrathin Al 2 O 3 film substrates obtained by the FeCrAl alloy oxidation. It is shown that at room temperature the model catalysts react with NO 2 with the successive formation of surface barium nitrite and nitrate. The NO 2 reduction with the formation of barium nitrite at the initial step of the interaction is assumed to be accompanied by the oxidation of residual metallic barium and amorphous carbon impurity. It is found that the formation of barium nitrate proceeds more efficiently on Ba/ZrO 2 rather than on Ba/TiO 2 .
The interaction of NO 2 with BaO/TiO 2 -ZrO 2 and Pt-BaO/TiO 2 -ZrO 2 model NO x storagereduction (NSR) catalysts prepared on the surface of FeCrAl alloy substrates has been investigated by X ray photoelectron spectroscopy. The action of nitrogen dioxide on these catalysts at room temperature causes the consecutive formation of surface barium nitrite and nitrate. Supposedly, NO 2 reduction yielding barium nitrite at the early stages of the interaction is due to the oxidation of amorphous carbon impurities. The intro duction of platinum into the catalyst accelerates nitrogen dioxide sorption. On being exposed to NO 2 for a long time, platinum oxidizes to PtO 2 . This process is more pronounced in the sample containing freshly deposited platinum. Heat treatment of this sample in a vacuum, which coarsens the platinum particles, makes them more resistant to oxidation.
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