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Hydrodechlorination of 4-chlorophenol in aqueous phase using Pd/AC catalysts prepared with modified active carbon supports

Paper ID Volume ID Publish Year Pages File Format Full-Text
48937 46531 2006 9 PDF Available
Title
Hydrodechlorination of 4-chlorophenol in aqueous phase using Pd/AC catalysts prepared with modified active carbon supports
Abstract

The hydrodechlorination of 4-chlorophenol with hydrogen in aqueous phase has been studied using different home-made Pd/active carbon catalysts. The active carbons employed were subjected to oxidation with nitric acid, hydrogen peroxide and ammonium persulfate and to thermal treatment under nitrogen atmosphere at temperatures ranging from 200 to 900 °C in order to modify their surface chemistry. High conversion values for 4-chlorophenol, well above 95%, were obtained working under mild conditions of temperature (50–75 °C) and pressure (2.4 bar). Modifications on the surface composition of the active carbon support upon oxidation and thermal treatment proved to affect to both conversion of 4-chlorophenol and selectivity towards cyclohexanol, the less toxic product in the reaction pathway. Increasing thermal treatment temperature showed to be detrimental in both respects whereas oxidation with nitric acid favored a higher selectivity to cyclohexanol. Those effects can be attributed more specifically to the relative presence of some oxygen groups on the surface of the support. Thus, the highest 4-chlorophenol conversions were obtained with the catalysts whose supports yielded higher amounts of CO2 upon temperature programmed desorption analysis. In particular, carboxylic acid and lactone groups where found to be relevant for a high conversion of 4-chlorophenol and their presence was also important to improve the selectivity to cyclohexanol. The presence of such groups can be related with a more homogeneous distribution of palladium on the catalysts surface.

Keywords
Surface oxygen groups; Active carbon; Palladium catalysts; Hydrodechlorination; 4-Chlorophenol
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Hydrodechlorination of 4-chlorophenol in aqueous phase using Pd/AC catalysts prepared with modified active carbon supports
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 67, Issues 1–2, 11 September 2006, Pages 68–76
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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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
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Any Questions? feel free to contact us