Isomorphously substituted Fe-MFI zeolite catalysts with various Si/Al and/or Si/Fe ratios were synthesized and characterized by many different techniques, such as ICP, XRD, SEM, TPR, microcalorimetry, FTIR, and EPR. Under standard reaction conditions the best catalyst gave 20% benzene conversion and over 90% selectivity to phenol. For Fe-ZSM5 catalysts, addition of steam to the feed improved catalyst activity, selectivity, and durability. Phenol formed onto Fe-based sites only. Active sites could very likely be composed of oxygen-bridged, extraframework binuclear Fe redox species, charge-compensating the framework Fe3+ or Al3+ ions. Surface acidity was not responsible for activity in the main reaction, but it was heavily involved in catalyst deactivation by coking. Catalyst deactivation derived mainly from the decomposition-condensation of phenol onto acid sites; the stronger the latter, the quicker was the coking rate.

Activity and deactivation of Fe-MFI catalysts for benzene hydroxylation to phenol by N2O / D. Meloni, R. Monaci, V. Solinas, G. Berlier, S. Bordiga, I. Rossetti, C. Oliva, L. Forni. - In: JOURNAL OF CATALYSIS. - ISSN 0021-9517. - 214:2(2003 Mar), pp. 169-178.

Activity and deactivation of Fe-MFI catalysts for benzene hydroxylation to phenol by N2O

I. Rossetti;C. Oliva;L. Forni
2003-03

Abstract

Isomorphously substituted Fe-MFI zeolite catalysts with various Si/Al and/or Si/Fe ratios were synthesized and characterized by many different techniques, such as ICP, XRD, SEM, TPR, microcalorimetry, FTIR, and EPR. Under standard reaction conditions the best catalyst gave 20% benzene conversion and over 90% selectivity to phenol. For Fe-ZSM5 catalysts, addition of steam to the feed improved catalyst activity, selectivity, and durability. Phenol formed onto Fe-based sites only. Active sites could very likely be composed of oxygen-bridged, extraframework binuclear Fe redox species, charge-compensating the framework Fe3+ or Al3+ ions. Surface acidity was not responsible for activity in the main reaction, but it was heavily involved in catalyst deactivation by coking. Catalyst deactivation derived mainly from the decomposition-condensation of phenol onto acid sites; the stronger the latter, the quicker was the coking rate.
Fe-MFI catalyst; benzene hydroxylation by N2O; catalyst acidity; catalyst coking
Settore CHIM/02 - Chimica Fisica
JOURNAL OF CATALYSIS
Article (author)
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/14805
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