Thermally-induced microstructural changes in a three-way automotive catalyst

Conference · Mon Dec 01 04:00:00 EST 1997

OSTI ID:554762

More, K L; Kenik, E A; Coffey, D W; Geer, T S ^[1]; Theis, J; LaBarge, W; Beckmeyer, R ^[2]

---

1. Oak Ridge National Lab., TN (United States)
2. Delphi Automotive Systems, Flint, MI (United States)

The use of advanced electron microscopy techniques to characterize both the bulk and near-atomic level microstructural evolution of catalyst materials during different dynamometer/vehicle aging cycles is an integral part of understanding catalyst deactivation. The study described here was undertaken to evaluate thermally-induced microstructural changes which caused the progressive loss of catalyst performance in a three-way automotive catalyst. Several different catalyst processing variables, for example changing the washcoat ceria content, were also evaluated as a function of aging cycle and thermal history. A number of thermally-induced microstructural changes were identified using high resolution electron microscopy techniques that contributed to the deactivation of the catalyst, including sintering of all washcoat constituents, {gamma}-alumina transforming to {alpha}-, {beta}-, and {delta}-alumina, precious metal redistribution, and constituent encapsulation. The data accumulated in this study have been used to correlate microstructural evolution with thermal history and catalyst performance during various aging cycles and to subsequently evaluate different washcoat formulations for increased thermal stability.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 554762
• Report Number(s): ORNL/CP--95239; CONF-971026--; ON: DE98000794; BR: EE5104000
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
AIR POLLUTION CONTROL
ALUMINIUM OXIDES
CARBON MONOXIDE
CATALYSTS
CATALYTIC CONVERTERS
CERIUM OXIDES
DEACTIVATION
HYDROCARBONS
MICROSTRUCTURE
MORPHOLOGICAL CHANGES
NITROGEN OXIDES
PLATINUM
RHODIUM
THERMAL DEGRADATION