Raman Studies of Automotive Catalyst Deactivation

Catalyst durability is a major concern in automotive exhaust gas treatment, and can be affected by chemical and thermal history. In this work, applications of in situ UV and visible Raman spectroscopy to a variety of catalyst deactivation issues are demonstrated: a) identification and characterizati...

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Bibliographic Details
Published in:SAE transactions 2006-01, Vol.115, p.136-143
Main Authors: Uy, Dairene, O'Neill, Ann E.
Format: Article
Language:English
Online Access:Get full text
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Summary:Catalyst durability is a major concern in automotive exhaust gas treatment, and can be affected by chemical and thermal history. In this work, applications of in situ UV and visible Raman spectroscopy to a variety of catalyst deactivation issues are demonstrated: a) identification and characterization of CePO₄ in three-way catalysts. CePO₄ forms from the interaction of phosphorus in engine oil additives with the catalyst washcoat. It affects oxygen storage and decreases catalyst conversion efficiency. b) thermal deactivation in Pd/ceria-zirconia catalysts. A compressive strain on palladium oxide as indicated by its Raman shift can serve as a diagnostic for a thermally-deactivated catalyst and thus the unavailability of the Pd for catalysis. c) sulfur poisoning, thermal deactivation and BaCO₃ formation in lean NOx traps (LNT). Spectral features demonstrate sulfation of LNT components, differences in fresh and thermally-aged Pt/Ba/Al₂O₃ which are consistent with results from activity and chemisorption measurements, and possible correlations of BaCO₃ formation to catalyst activity.
ISSN:0096-736X
2577-1531