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Investigation of the Impact of Real-World Aging on Diesel Oxidation Catalysts
Abstract:
Real-world operation of diesel oxidation catalysts (DOCs), used
in a variety of aftertreatment systems, subjects these catalysts to
a large number of permanent and temporary deactivation mechanisms.
These include thermal damage, induced by generating exotherm on the
catalyst; exposure to various inorganic species contained in engine
fluids; and the effects of soot and hydrocarbons, which can mask
the catalyst in certain operating modes. While some of these
deactivation mechanisms can be accurately simulated in the lab,
others are specific to particular engine operation regimes.
In this work, a set of DOCs, removed from prolonged service in
the field, has been subjected to a detailed laboratory study.
Samples obtained from various locations in these catalysts were
used to characterize the extent and distribution of deactivation.
The arsenal of techniques used to characterize the samples included
probe reactions of NO and C₃H₆ oxidation, as well as a set of
pre-treatment conditions, targeting at removing various
contaminants, including hydrocarbons, soot, sulfur, and
phosphorous.