AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThA

Paper SS1-ThA7
NOx Storage Capacity and Thermal Aging of BaO/theta-Al2O3/NiAl(100) Model Catalyst

Thursday, November 16, 2006, 4:00 pm, Room 2002

Session: Reactivity of Oxide Surfaces II
Presenter: J. Szanyi, Pacific Northwest National Laboratory
Authors: J. Szanyi, Pacific Northwest National Laboratory
E. Ozensoy, Pacific Northwest National Laboratory
C.H.F. Peden, Pacific Northwest National Laboratory
Correspondent: Click to Email
NOx storage behavior of a BaO/θ-Al2O3/NiAl(100) model catalytic system during NO2 adsorption was studied via X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) techniques; and compared to that of the θ-Al2O3/NiAl(100) support material and a thermally-aged BaO/θ-Al2O3/NiAl(100) model catalyst at 1100K. At T > 300 K, adsorbed NO2 is converted to nitrates on all of the surfaces studied. Nitrates that are residing on the alumina sites of the model catalyst surfaces are relatively weakly bound and typically desorb within 300 K-600 K, leading to NO(g) evolution; while nitrates associated with the baria sites are significantly more stable and desorb within 600 K- 850 K, resulting in NO(g) or NO(g)+O2(g) evolution. NOx uptake by the baria sites of the BaO/θ-Al2O3/NiAl(100) model catalyst surface was found to be as high as a factor of five with respect to that of the θ-Al2O3/NiAl(100) support material. Thermal aging of a BaO/θ-Al2O3/NiAl(100) model catalyst surface at 1100 K prior to NOx uptake experiments, brings about a significant (70 %) reduction in the NOx storage capacity of the model catalyst surface.