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Effect of preparation and metal content on the introduction of Fe in BEA zeolite, studied by DR UV-vis, EPR and Mössbauer spectroscopy |
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| Authors: | Stanislaw Dzwigaj Lorenzo Stievano Michel Che |
| Affiliation: | a Laboratoire de Réactivité de Surface, UMR 7609-CNRS, Université Pierre et Marie Curie, Case 178, 4 Place Jussieu, 75252 Paris Cedex 05, France b Physik-Department E15, Technische Universität München, James-Franck Strasse, 85747 Garching, Germany c Institut Universitaire de France, France |
| Abstract: | Fe-containing SiBEA zeolites were prepared by a two-step postsynthesis method: creation of vacant T-sites by dealumination of tetraethylammonium BEA zeolite with nitric acid and then impregnation of the resulting SiBEA zeolite with an aqueous solution of Fe(NO3)3. X-ray diffraction shows that iron is incorporated in SiBEA at lattice sites. The presence of Fe in its oxidation state +3 and at isolated tetrahedral sites for low metal content, was demonstrated by diffuse reflectance UV-vis, EPR and Mössbauer spectroscopy. For high iron content, diffuse reflectance UV-vis and Mössbauer spectra revealed the additional presence of extra-lattice FeOx oligomers and superparamagnetic Fe-oxyhydroxide. Mössbauer spectroscopy identified superparamagnetic Fe-oxyhydroxide as the main phase when basic conditions are used for the preparation. |
| Keywords: | A. Microporous materials B. Chemical synthesis C. Mö ssbauer spectroscopy D. Electron paramagnetic resonance D. Microstructure |
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