Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 9: Oxides and Insulators: Adsorption I
O 9.5: Vortrag
Montag, 26. März 2007, 12:15–12:30, H42
Ammonia adsorption on V2O5 - DFT custer model studies — •Malgorzata Witko and Pawel Hejduk — Institute of Catalysis and Surface Chemistry, PAS, ul. Niezapominajek 8, 30 239 Krakow, Poland
Catalysts based upon vanadia are used in many processes belonging to very different types of chemical reactions, among them to the selective catalytic reduction of NOx by NH3. Although the last mentioned reaction is of a great technological importance its mechanism is still under debate. In order to understand the details of the process the adsorption on ammonia on hydoxyl groups existing on different low-indices (010), (100) and (001)V2O5 surfaces will be discussed based upon cluster model DFT calculations within GGA-RPBE functional. The results of the performed calculations indicate spontaneous stabilization of NH3 at any surface hydroxyl groups with the adsorption energy in the range of 0.8 to 1.3 eV. Ammonia becomes adsorbed in various geometries and the reaction proceeds according to different mechanism depending on the type of oxygen forming OH group and on the type of surface. In all cases the significant role of hydrogen bonds of different strengths is found.