Quantitative Determination of Isolated Fe3+ Cations in FeHZSM-5 Catalysts by ESR

A method for the quantitative determination of isolated Fe3+ ions in FeHZSM-5 by EPR was devised. The method is based on the comparison of signals, taken at −196°C, from pyridine-impregnated catalysts with signals from solutions of Fe(III)-phthalocyanine in pyridine. FeCl3 was introduced into HZSM-5...

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Bibliographic Details
Published in:Journal of catalysis 2000-10, Vol.195 (1), p.106-112
Main Authors: Kucherov, A.V., Shelef, M.
Format: Article
Language:English
Subjects:
Catalysis
Catalysts: preparations and properties
Chemistry
electron spin resonance
Exact sciences and technology
General and physical chemistry
HZSM-5
quantitation of Fe3+ ions
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
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Summary:A method for the quantitative determination of isolated Fe3+ ions in FeHZSM-5 by EPR was devised. The method is based on the comparison of signals, taken at −196°C, from pyridine-impregnated catalysts with signals from solutions of Fe(III)-phthalocyanine in pyridine. FeCl3 was introduced into HZSM-5 having Si/Al ratios of 15 and 25. The amount of Fe was between 0.5 and 5.5 wt%. The samples were prepared either by sublimation of FeCl3 into the zeolite in an N2 flow or by impregnation with FeCl3 water solutions, and subsequently calcined at 400–800°C. The measurement of “ESR-visible Fe3+” in FeCl3/HZSM-5 calcined at 400°C in vacuum demonstrates that virtually all ferric ions, present as isolated FeCl+2-species, contribute to the ESR signal in samples with Fe/Al ratios
ISSN:0021-9517
1090-2694
DOI:10.1006/jcat.2000.2976