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Re-dispersion of Pd on Ce0.5Zr0.5O2 upon cooling in the presence of oxygen

Paper ID Volume ID Publish Year Pages File Format Full-Text
53422 46969 2015 6 PDF Available
Title
Re-dispersion of Pd on Ce0.5Zr0.5O2 upon cooling in the presence of oxygen
Abstract

•Re-dispersion of Pd on Ce0.5Zr0.5O2 was observed during slow cooling in oxidizing atmosphere.•Sufficient cooling time, O2, and active support were the essential factors for re-dispersion.•Sintered Pd particles were re-oxidized to PdOx and re-dispersed under the driving of the formation of PdOCe bonds.

Pd/Ce0.5Zr0.5O2 catalyst was prepared by impregnation method and subjected to different cooling procedures (rapid cooling vs. slow cooling in O2 or in He) after pretreated at 950 °C for 30 min. The obtained catalysts were characterized by CO chemisorption, transmission electron microscope (TEM), CO temperature-programmed oxidation (CO-TPO), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The results revealed that Pd species on Ce0.5Zr0.5O2 (CZ) suffered severe sintering during high-temperature calcination, but the Pd dispersion increased remarkably after slow cooling in O2. Further investigations ascribed this phenomenon to the Pd re-dispersion process, which needed three essential factors, i.e. sufficient cooling time, oxidizing atmosphere and active support which had strong interaction with Pd species. The re-dispersion process was proved to be mainly due to both the re-oxidization of the sintered Pd particles and the slow migration of the PdOx under the driving of the interaction between Pd and CZ.

Graphical abstractScheme of the re-dispersion process of Pd on the Ce0.5Zr0.5O2 support in O2 at different cooling rates.Figure optionsDownload full-size imageDownload high-quality image (114 K)Download as PowerPoint slide

Keywords
Palladium; Ceria–zirconia; Re-dispersion; Cooling; Interaction
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Re-dispersion of Pd on Ce0.5Zr0.5O2 upon cooling in the presence of oxygen
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 253, 15 September 2015, Pages 51–56
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