Detection, Origin and Effect of Ultra-Low Platinum Contamination on Diesel-SCR Catalysts
This paper discusses the poisoning of a selective catalytic reduction (SCR) catalyst by trace levels of platinum originating from an upstream diesel oxidation catalyst (DOC). A diesel aftertreatment system consisting of a DOC, urea based SCR Catalyst and a DPF was aged and evaluated on a 6.4 liter d...
Gespeichert in:
Veröffentlicht in: | SAE International journal of fuels and lubricants 2009-04, Vol.1 (1), p.1553-1559, Article 2008-01-2488 |
---|---|
Hauptverfasser: | , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | This paper discusses the poisoning of a selective catalytic reduction (SCR) catalyst by trace levels of platinum originating
from an upstream diesel oxidation catalyst (DOC). A diesel aftertreatment system consisting of a DOC, urea based SCR Catalyst
and a DPF was aged and evaluated on a 6.4 liter diesel engine dynamometer. The SCR catalyst system consisted of an Fe-zeolite
catalyst followed by a Cu-zeolite catalyst. After approximately 400 hours of engine operation at varied exhaust flow rates
and temperatures, deactivation of the SCR catalyst was observed. A subsequent detailed investigation revealed that the Cu
catalyst was not deactivated and the front half of the Fe-based catalyst showed severe deactivation. The deactivated portion
of the catalyst showed high activity of NH 3 conversion to NO x and N 2 O formation. The cause of the deactivation was identified to be the presence of trace Pt contamination. The contamination
level was less than 0.002wt% that could not easily be detected by a conventional X-ray fluorescence (XRF) method. The detection
of trace Pt was made at first using a newly developed ethylene hydrogenation reaction method. The reaction system was built
in-house for measuring the conversion of ethylene to ethane at room temperature over a catalyst monolith core. The system
allowed the detection of Pt metal below 0.001wt%. The presence of Fe, Cu, or Ni did not interfere with the ethylene hydrogenation
technique. The sublimation of Pt from an upstream DOC onto Fe-based catalysts was demonstrated experimentally in the laboratory
using the new technique. In the after treatment system studied, the Fe catalyst acted as a buffer to trap Pt sublimed from
the upstream DOC shielding the Cu catalyst from Pt contamination. The effect of DOC aging conditions on Pt sublimation and
subsequent Pt contamination on the downstream SCR catalyst was also investigated. |
---|---|
ISSN: | 1946-3952 1946-3960 1946-3960 |
DOI: | 10.4271/2008-01-2488 |