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Combustion process and exhaust gas aftertreatment in the Mercedes-Benz Bluetec concept
Abstract
In recent years, Mercedes-Benz has frequently reached important emission control milestones in diesel engines: In 1985, the world’s first serial production particulate filter for passenger cars, in 2003 the first modern particulate filter with additive-free regeneration, and, in October 2006, the United States market launch of the E 320 Bluetec. This vehicle is the first serial production diesel passenger car to exceed the requirements of U.S. Tier II Bin 8 standards. The Bluetec concept is based on several building blocks: the base engine with significantly reduced engine out emissions, the oxidation catalyst and particulate filter, the nitrous oxide aftertreatment, and the associated system control.
In October 2006 when Mercedes-Benz introduced the model E 320 Bluetec, it brought the first production diesel passenger car to the market that met US Tier 2 Bin8 emission standards. Mercedes-Benz will continue its Bluetec offensive in 2008, offering the V6 diesel engine in the M, GL and R Classes in the USA, using the SCR/AdBlue technology which meets the US Tier 2 Bin5 emission standards and thereby all currently valid emission standards for diesel passenger cars worldwide.
At the Institute for Combustion Engines of the Technical University of Kaiserslautern, a potential analysis and some basic tests for the use of the SCR-Technology at lean mixture direct-injection gasoline engines were conducted based on year-long experience with selective catalytic reduction at the exhaust gas of diesel engines. The main focus was on the aspects of consumption of reducing agent and achievable conversion of nitrogen oxides.
Investigations of the aging behavior induced by high temperatures coupled with oxidizing atmosphere of model NOx
storage systems Ba/Al2O3 and Ba/CeO2 are reported in this paper. The samples were prepared, calcined and exposed to temperatures between 500 and 1000 °C in air for 12 h for thermal aging. Samples were characterized with XRD, HRSEM, DSC-TGA-MS and BET analyses. In XRD investigations of all model systems calcined at 500 °C for 2 h, the NOx
storage component was present in form of BaCO3. The release of CO2 as a result of the decarbonization of the NOx
storage component at increased temperatures was verified by thermogravimetric investigations. In the case of Ba/Al2O3, already during calcination a partial reaction of the NOx
storage component with Al2O3 resulting in the formation of barium aluminate was observed. In the model system Ba/CeO2 the decomposition of the barium carbonate started above 780 °C and the formation of a barium cerium mixed oxide was observed. The presence of the barium containing NOx
storage component has a strong influence on the specific surface area of the model NOx
storage systems. The morphology and crystallite size of CeO2 modified with the barium containing NOx
storage component exhibited distinct changes compared to the unmodified oxide. The NOx
storage efficiency determined by model gas tests of freshly prepared and engine aged model NOx
storage catalysts correlates well with the above described observations.
Selective Catalytic Reduktion mit Harnstoff - Der effektive Weg zur Stickoxidminderung am Pkw-Dieselmotor [Selective Catalytic Reduction with urea - the effective path to nitrous oxide reduction in passenger car diesels
- C Enderle
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- C. Enderle
Das neue Mercedes-Benz Dieselpartikelfilter-Konzept für Pkw in Verbindung mit der Abgasstufe Euro 4 [The new Mercedes-Benz diesel particulate filter concept for passenger cars in relation to Euro 4 exhaust gas limits
- J Schommers
- J. Schommers
Potenziale und Grenzen der Abgasnachbehandlung durch NOx-Speicherkatalysatoren [Potential and limits of exhaust-gas after-treatment using NOx storage catalysts
- H. Breitbach
Emissionsstrategie Dieselantriebe [Diesel power emissions strategy], VDA Technical Congress
- L. Mikulic
Verhalten von SCR-Katalysatoren in dieselmotorischem Abgas [Behavior of SCR catalysts in diesel exhaust gas
- G. Lepperhoff
Potenziale und Grenzen der Abgasnachbehandlung durch NOx-Speicherkatalysatoren [Potential and limits of exhaust-gas after-treatment using NOx storage catalysts
- H Breitbach
- Chr Schön
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- H. Breitbach
Emissionsstrategie Dieselantriebe
- L Mikulic
- J Schommers
- H Breitbach
- L. Mikulic
Verhalten von SCR-Katalysatoren in dieselmotorischem Abgas [Behavior of SCR catalysts in diesel exhaust gas
- G Lepperhoff
- J Schommers
- G. Lepperhoff