The Impact of Pressure and Hydrocarbons on NOx Abatement over Cu- and Fe-Zeolites at Pre-Turbocharger Position

Positioning the catalysts in front of the turbocharger has gained interest over recent years due to the earlier onset temperature and positive effect of elevated pressure. However, several challenges must be overcome, like presence of higher pollutant concentrations due to the absence or insufficien...

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Bibliographic Details
Published in:Catalysts 2021-03, Vol.11 (3), p.336
Main Authors: Zengel, Deniz, Barth, Simon, Casapu, Maria, Grunwaldt, Jan-Dierk
Format: Article
Language:English
Subjects:
Ammonia
Atmospheric pressure
Catalysts
Catalytic activity
Catalytic oxidation
Chemical reactions
Chemical reduction
Hydrocarbons
Hydrogen cyanide
Investigations
Nitrogen oxides
Oxidation
Pollutants
Pressure effects
Selective catalytic reduction
Superchargers
Zeolites
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Summary:Positioning the catalysts in front of the turbocharger has gained interest over recent years due to the earlier onset temperature and positive effect of elevated pressure. However, several challenges must be overcome, like presence of higher pollutant concentrations due to the absence or insufficient diesel oxidation catalyst volume at this location. In this context, our study reports a systematic investigation on the effect of pressure and various hydrocarbons during selective catalytic reduction (SCR) of NOx with NH3 over the zeolite-based catalysts Fe-ZSM-5 and Cu-SSZ-13. Using a high-pressure catalyst test bench, the catalytic activity of both zeolite catalysts was measured in the presence and absence of a variety of hydrocarbons under pressures and temperatures resembling the conditions upstream of the turbocharger. The results obtained showed that the hydrocarbons are incompletely converted over both catalysts, resulting in numerous byproducts. The emission of hydrogen cyanide seems to be particularly problematic. Although the increase in pressure was able to improve the oxidation of hydrocarbons and significantly reduce the formation of HCN, sufficiently low emissions could only be achieved at high temperatures. Regarding the NOx conversion, a boost in activity was obtained by increasing the pressure compared to atmospheric reaction conditions, which compensated the negative effect of hydrocarbons on the SCR activity.
ISSN:2073-4344
2073-4344
DOI:10.3390/catal11030336