Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 8: Surface Chemical Reactions and Heterogeneous Catalysis I
O 8.6: Vortrag
Montag, 11. März 2013, 11:45–12:00, H33
Identifying Cu(I) Cationic Positions in SSZ-13 by Modeling Infrared and Diffuse Reflectance Spectra — •Florian Göltl1, Philippe Sautet1, Kerstin Hummer2, Georg Kresse2, and Jürgen Hafner2 — 1University of Lyon I, ENS Lyon, Allee d’Italie 46, 69342 Lyon, France — 2University of Vienna, Faculty of Physics, Computational Materials Physics, Sensengasse 8/12, 1090 Vienna, Austria
Copper containing zeolites are prime candidates in removing nitrous oxides from exhaust gases. Recently an especially high activity of Cu containing SSZ-13 for the given reaction has been shown in experiment. However, the exact cationic positions within this material have been debated. Based upon the catalyst preparation process we suggest a new type of Cu(I) site within SSZ-13. We use density functional to model different active sites and the IR spectrum of adsorbed CO. We find two different peaks, one redshifted by 2-5 cm−1, the other one red-shifted by 15 cm−1. Furthermore we calculate the optical absorption spectra of those sites using Bethe-Salpeter Equation on top of self consistent GW0 calculations. Compared to hybrid functoinal calculations the GW0 approximation increases the energy gap between Cu 3d- and 4s states by about 2 eV. On the other hand, excitonic effects calculated within Bethe-Salpeter Equation reduce this gap upon optical absoption by about 3 eV, which leads to absorption maxima for the Cu d-s transition of 4 eV and between 4.5 and 4.7 eV for different cationic sites. Our calculations agree perfectly with experiment.