Thermally Induced Structural Evolution of Palladium‐Ceria Catalysts. Implication for CO Oxidation

Structural transformations in Pd/CeO2 catalysts during their calcination over a wide temperature range (450‐1200 °C) were studied with structural, spectroscopic, and kinetic methods (XRD, TEM, XPS, and TPR). Two synthetic methods were applied: coprecipitation and incipient wetness impregnation. The...

Full description

Saved in:
Bibliographic Details
Published in:ChemCatChem 2019-08, Vol.11 (15), p.3505-3521
Main Authors: Stonkus, Olga A., Kardash, Tatyana Yu, Slavinskaya, Elena M., Zaikovskii, Vladimir I., Boronin, Andrei I.
Format: Article
Language:English
Subjects:
Agglomerates
Catalysis
Catalysts
cerium oxide
Cerium oxides
CO oxidation
Coprecipitation
Impregnation
Moisture content
Morphology
Nanoparticles
Oxidation
Palladium
Roasting
Solid solutions
Structure-activity relationships
Superstructures
Synthesis
Thermal stability
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Structural transformations in Pd/CeO2 catalysts during their calcination over a wide temperature range (450‐1200 °C) were studied with structural, spectroscopic, and kinetic methods (XRD, TEM, XPS, and TPR). Two synthetic methods were applied: coprecipitation and incipient wetness impregnation. The impregnation synthesis produced the best low‐temperature oxidation of CO (LTO CO) for the catalysts that were calcined at 450–900 °C. Their high LTO CO activities could be attributed to the formation of reactive surface clusters at the PdO−CeO2 interface. The coprecipitation synthesis produced a homogeneous PdxCe1‐xO2‐δ solid solution with no Pd nanostructured particles. Decomposition of the solid solution phase occurred at 800–850 °C and resulted in the formation of unusual Pd species, i. e., Pd(Ce)Ox superstructures and agglomerates consisting of 2 nm PdO particles. Further calcination of the catalysts resulted in the formation of mixed Pd0−PdO−CeO2 nanoparticles with a heterophase morphology that provided high thermal stability. These catalysts demonstrated capability for CO oxidation at temperatures below 100 °C after calcination at 1200 °C. Step by step: The structural evolution of the active component of Pd/CeO2 catalysts during thermal treatment proceeds stepwise from an atomically dispersed state to a nanostructured state. The roles of different Pd states in CO oxidation were elucidated.
ISSN:1867-3880
1867-3899
DOI:10.1002/cctc.201900752