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Decomposition and/or hydrogenation of hydrogen peroxide over Pd/Al2O3 catalyst in aqueous medium: Factors affecting the rate of H2O2 destruction in presence of hydrogen

Paper ID Volume ID Publish Year Pages File Format Full-Text
43426 45969 2007 9 PDF Available
Title
Decomposition and/or hydrogenation of hydrogen peroxide over Pd/Al2O3 catalyst in aqueous medium: Factors affecting the rate of H2O2 destruction in presence of hydrogen
Abstract

Hydrogen peroxide destruction by its decomposition and/or hydrogenation to water in the presence of H2 over Pd(5 wt.%)/Al2O3 catalyst in an aqueous reaction medium, similar to that used in the H2-to-H2O2 oxidation, has been thoroughly investigated at different reaction conditions. The H2O2 destruction is strongly influenced by the oxidation state of Pd in the catalyst and also by the presence of different halide anions (viz. F−, Cl−, Br− and I−) in the acidic aqueous medium or in the catalyst, depending upon the concentration of halide anions. The cations associated with halide anions have, however, a little or no influence on the H2O2 destruction. The iodide anions strongly poisoned the catalyst, even at their very low concentration. The fluoride anions have only a small effect on the H2O2 destruction. The chloride or bromide anions drastically inhibit the rapid H2O2 decomposition, but promote the slower H2O2 hydrogenation. The H2O2 destruction reactions are strongly influenced by the halide anion and acid concentrations. The presence of acid (protons) plays a very important role in drastically reducing the H2O2 destruction, particularly in the presence of chloride anions. Both in the presence and absence of Cl− or Br− anions, the H2O2 destruction activity of the catalyst is markedly reduced because of the oxidation of Pd but it is drastically increased due to the presence of H2. A plausible reaction mechanism for the rapid H2O2 decomposition and slower H2O2 hydrogenation reactions, prevailing under the different reaction conditions, has also been discussed.

Graphical abstractThe destruction of H2O2 by its decomposition and/or hydrogenation over Pd/Al2O3 catalyst is strongly influenced by the presence of H2, nature of halide anions (F−, Cl−, Br− or I−) in the reaction medium or in the catalyst, concentration of halide anions and protons (acid) in the medium and oxidation state of Pd in the catalyst.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Hydrogen peroxide; Decomposition of H2O2; Hydrogenation of H2O2; Pd/Al2O3; Halide anions as catalyst promoter or indicator
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Decomposition and/or hydrogenation of hydrogen peroxide over Pd/Al2O3 catalyst in aqueous medium: Factors affecting the rate of H2O2 destruction in presence of hydrogen
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 332, Issue 1, 1 November 2007, Pages 70–78
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