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In situ generation of hydrogen peroxide in catalytic membrane reactors

Paper ID Volume ID Publish Year Pages File Format Full-Text
55072 47039 2012 9 PDF Available
Title
In situ generation of hydrogen peroxide in catalytic membrane reactors
Abstract

Commercial ceramic hollow fibres have been used as a starting material for the preparation of catalytic membrane reactors (CMRs). The original nominal pore sizes of the membranes were 4, 20, 100, 500 and 1400 nm. The CMRs have been produced by palladium precursor impregnation followed by calcinations and reduction in hydrogen flow at 350 °C. The direct generation of hydrogen peroxide from hydrogen and oxygen has been studied at ambient conditions. The efficiency of hydrogen peroxide generation, with respect to hydrogen supply, as well as the rate of H2O2 production and the maximum H2O2 concentration as a function of the original membrane pore size have been determined. The μ-XRD and SEM analyses have revealed that the Pd is uniformly distributed throughout the entire membranes. The rate of hydrogen peroxide generation has been shown to depend inversely on the membrane pore size. It has been demonstrated that the upper hydrogen peroxide concentration level is set by the catalyst deactivation and therefore not caused by reverse reactions or hydrogen peroxide reduction by the activated hydrogen. This finding has been confirmed by the XPS analysis.The in situ oxidation of phenol by a subsequent heterogeneous Fenton process in phenol-containing water has been assessed using the CMRs prepared. In these cases no significant activity has been detected. Addition of Fe(II) to the reaction solution has resulted in CMRs with considerable activity for phenol oxidation.In another series of ceramic hollow fibre membranes, the Pd impregnation was preceded by the incorporation of a second active phase (Fe2O3, CuAl2O4, TiO2 or CeO2). The rates of hydrogen peroxide generation as well as the maximum H2O2 concentration for these bi-functional CMRs have been determined following the same procedure developed for the first series of CMRs. All of them have shown activity in producing H2O2. The initial tests for phenol oxidation by the in situ generated H2O2 have demonstrated the viability of the proposed reaction system for waste water treatment.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (200 K)Download as PowerPoint slideHighlights► Three phase contact. ► Better distribution of the gases. ► Lower active phase deactivation. ► The addition of second active phase (transition metal oxide) results in heterogeneous Fenton process.

Keywords
Hydrogen peroxide generation; Catalytic membrane reactor; Palladium deactivation; Bi-functional catalytic membrane reactors; Phenol oxidation
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In situ generation of hydrogen peroxide in catalytic membrane reactors
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 193, Issue 1, 15 October 2012, Pages 128–136
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