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Washcoating method for Pd/γ-Al2O3 deposition on metallic foams

Paper ID Volume ID Publish Year Pages File Format Full-Text
49129 46552 2006 11 PDF Available
Title
Washcoating method for Pd/γ-Al2O3 deposition on metallic foams
Abstract

A method for coating open celled metal foams with a thin layer of Pd–Al2O3 was developed. The method makes use of a sol–gel of pseudobohemite as a precursor of γ-Al2O3 to fill the porous structure by percolation whilst the excess of material is flushed away with an air jet. The influence of solid content, acid content and ageing on the sol–gel rheological behaviour was studied to find a sol–gel dispersion with an appropriate viscosity whose deposition resulted in a 20 μm thick coating layer. Foam samples of different nominal porosities (10, 20 and 40 PPI) were coated with this method and activated with palladium using a wet impregnation procedure with loadings of 3% (w/w) palladium on the alumina.As an alternative approach, dry impregnation of γ-Al2O3 with palladium was performed and a slurry was prepared adding water and nitric acid. The slurry was deposited by percolation through the foam structure. The coating quality was evaluated with adhesion tests and the activity of coated foams was measured by performing catalytic oxidation of CO in a 9 mm i.d. tubular reactor. Both methods produced highly active foams, resulting in light off temperatures between 175 and 250 °C depending on CO concentration. Moreover, the mass transfer controlled regime was achieved in all runs independently of the coating method. Nevertheless, conversions reached when the sol–gel dispersion was deposited and activated via wet impregnation were higher than the ones obtained with the coating method based on slurry deposition of active powders, indicating that the sol–gel deposition resulted in more uniform coating.

Keywords
Metal foams; Catalyst supports; Coating procedures
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Washcoating method for Pd/γ-Al2O3 deposition on metallic foams
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 62, Issues 1–2, 10 January 2006, Pages 121–131
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