Regensburg 2007 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: POSTER: INTERNAL SYMPOSIUM Optical Spectrosopy

CPP 22.1: Poster

Mittwoch, 28. März 2007, 16:00–18:30, Poster B

FTIR and EPR Studies of the Adsorption Complexes of Benzene and Oxygen on Cu/HZSM5 Zeolites — •Augusta Ene, Tanja Archipov, and Emil Roduner — Institute of Physical Chemistry, University of Stuttgart

Today phenol is produced mostly by the Cumene process, a three-step process which yields phenol and acetone in an 1:1 ratio. An alternative to this synthesis is the oxidation of benzene to phenol with molecular oxygen on Cu-exchanged zeolite catalysts. In order to understand the catalytic process on a molecular level one needs to understand the structures and geometry of the reactants on the surface. Vibrational spectroscopy offers information on both the strength of the acid sites and the nature of the adsorbate. Thus we study the adsorption complexes of benzene and oxygen on Cu-containing and Cu-free HZSM-5 zeolites by means of FTIR spectroscopy in order to determine the orientation of the adsorbed molecules on the zeolite surface. As the Cu²⁺ ions (3/2 spin) are EPR active, the oxidations state of Cu can be observed as well. Information on the surroundings of the active Cu species can be gained from the g and hyperfine anisotropy, offering us the chance to determine which Cu containing sites are more active during the catalytic process.