NOx Abatement by Catalytic Traps: On the Mechanism of NOx Trapping Under Automotive Conditions |
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Authors: | Marcus Hilgendorff |
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Affiliation: | (1) Engelhard Technologies GmbH, Freundallee 23, 30173 Hanover, Germany |
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Abstract: | NO
x
adsorption was measured with a barium based NOx storage catalyst at an engine bench equipped with a lean burn gasoline direct injection engine (GDI). In order to study the influence of gas phase NO2 on the NOx storage efficiency two different pre-catalysts were used: One with excellent NO oxidation activity to produce a high NO2 concentration and another pre-catalyst without NO oxidation activity and therefore high NO concentration at the NO
x
storage catalyst inlet. Both pre-catalyst had excellent HC and CO conversion efficiency and therefore the CO and HC concentration at the NO
x
storage catalyst inlet was practically zero. No lean NO
x
reduction was observed. Under that conditions, experiments with NO
x
storage catalysts of different length show that a high NO2 inlet concentration did not enhance the NO
x
storage efficiency. Moreover, we observed reduction of NO2 to NO over the NOx storage catalyst. However, in presence of a high NO inlet concentration NO2 formation was observed which may proceed parallel to NO
x
storage. |
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Keywords: | GDI lean NO
x
trap engine bench NO
x
adsorption NO2 |
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