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Indications of the reactive species in a heterogeneous Fenton-like reaction using Fe-containing zeolites

Paper ID Volume ID Publish Year Pages File Format Full-Text
41592 45894 2011 10 PDF Available
Title
Indications of the reactive species in a heterogeneous Fenton-like reaction using Fe-containing zeolites
Abstract

Heterogeneous Fenton-like reactions have potential applications in wastewater treatment. Recently, the use of zeolites containing iron species as catalysts in Fenton-like processes has gained increasing interest. While it has been assumed in the literature that hydroxyl radicals (OH) are the dominant reactive species formed from H2O2 in the presence of Fe-zeolites, no direct evidence for this hypothesis exists so far. This work aims at the elucidation of the type of reactive species involved in the heterogeneous Fenton reaction using the Fe-containing zeolites Fe-ZSM5 and Fe-Beta. Electron paramagnetic resonance (EPR) measurements using dimethyl pyrroline-N-oxide (DMPO) as spin trap were carried out; the formation of the complex DMPO-OH was observed, which is often ascribed to a reaction with OH. However, significant differences were found in the kinetic deuterium isotope effect (KDIE) for methanol oxidation between the heterogeneous Fenton-like reaction and genuine OH reactions initiated by the homogeneous Fenton reaction. The KDIE for methanol oxidation in the heterogeneous reaction increased from 1.33 to 1.41 with increasing concentration of the OH scavenger bicarbonate, whereas the KDIE in the classical Fenton reaction is 1.07 and unaffected by the presence of quenchers. The significantly different values are a clear indication for the participation of additional oxidants beside OH. In addition, Fe-zeolites catalyzed the epoxidation of cyclohexene by H2O2. This type of reaction suggests the participation of a high-valent oxoiron complex (ferryl) in the wet peroxide oxidation of organic compounds catalyzed by Fe-zeolites.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (133 K)Download as PowerPoint slideHighlights► Different KDIE for methanol in heterogeneous and homogeneous Fenton reactions. ► Scavenging experiments revealed that more than one oxidant species is involved. ► Additional oxidant reacts with a higher selectivity and lower reactivity than OH. ► According to the results, this additional oxidant could be a ferryl species.

Keywords
Heterogeneous Catalysis; Fenton; Zeolites; Hydroxyl Radical; Ferryl
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Indications of the reactive species in a heterogeneous Fenton-like reaction using Fe-containing zeolites
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 398, Issues 1–2, 15 May 2011, Pages 44–53
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us