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Pd–Cu interaction in Pd/Cu-MCM-41 catalysts: Effect of silica source and metal content

Paper ID Volume ID Publish Year Pages File Format Full-Text
54221 47001 2015 8 PDF Available
Title
Pd–Cu interaction in Pd/Cu-MCM-41 catalysts: Effect of silica source and metal content
Abstract

•The presence of Pd and Cu does not alter MCM-41 structure in silicate-derived samples.•The long range order is lower for TEOS-derived samples.•Pd1−xCuxO particles are obtained, larger Cu2+ into PdO for TEOS-derived samples.•TEOS derived catalysts were more selective to the target CF3OCFCF2 product.

Pd/Cu-MCM-41 catalysts for the hydrodechlorination of CF3OCFClCF2Cl to CF3OCFCF2 were prepared. Palladium- and copper-containing samples (Pd/Cu = 1 molar ratio) were synthesized by adding Pd2+ and Cu2+ during the formation of MCM-41, and then the slurries were aged by microwave-hydrothermal treatment. The effect of the silica source (silicates or TEOS) and total metal loading (2.4 and 4.0 wt.%) on the chemical–physical properties and catalytic performances was studied. Bimetallic silicate-derived samples show features similar to those of the pristine MCM-41, regardless of the total metal content. Conversely, the long-range order of the mesoporous structure decreases for TEOS-derived catalysts, and large metal contents seem to alter the structure for these materials.During template removal by thermal treatment, palladium and copper are on the surface of MCM-41 particles, forming Pd1−xCuxO solid solutions whose composition is silica source-dependent. The amount of copper in Pd1−xCuxO is greater for TEOS-derived samples.After reduction, both Pd- and Cu-enriched alloys were found by XRD in silicate-derived samples, while XPS measurements indicated that the surface of the catalyst is enriched with copper. XRD and XPS analyses on TEOS samples indicated that the surface Cu/Pd ratio is closer to 1, and fcc PdCu alloys with a high copper content were identified. The composition of metallic particles modifies the selectivity, TEOS-derived catalysts being more selective to the target CF3OCFCF2.

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Keywords
Palladium; Copper; MCM-41; Silicate; TEOS; Hydrodechlorination
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 246, 15 May 2015, Pages 108–115
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
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Full-text PDF Download
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