Probing the Redox States of Iron in Steam-Treated Isomorphously Substituted [Fe,Al]MFI Catalyst
- Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)
- Biocatalysis and Organic Chemistry, Department of Biotechnology, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands)
- Reactor and Catalysis Engineering, DelftChemTech, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands)
57Fe enriched isomorphously substituted [Fe,Al]MFI zeolites with varying aluminum content were prepared and subsequently calcined, proton-exchanged, and steamed to render them active in the direct oxidation of benzene to phenol using N2O as oxidant. The different post-treatment steps cause the migration of iron from framework to extra-framework positions creating various Fe-sites as deduced from 57Fe Moessbauer spectroscopy. An extraordinary high concentration of Fe2+ species (which were correlated to the formation of {alpha}-sites that was claimed to be responsible in the catalytic benzene-to-phenol reaction) was obtained for the sample containing 1.1% w/w aluminum. On the contrary, for the aluminum-free sample (Fe-silicalite) only Fe3+ species were observed. In-situ Fe K-edge XANES were performed to study the reactivity of the Fe-species in the steamed samples under reducing/oxidizing environment. Reduction-oxidation (redox) behavior was observed only for aluminum-containing samples, whereas the Fe3+ species in the Fe-silicalite maintain their oxidation state.
- OSTI ID:
- 20722151
- Journal Information:
- AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 765; ISSN APCPCS; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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