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Strategic Materials at Reaction Temperatures (SMART) is an approach used to design washcoat systems for passive 4-way emission control catalysts. Light duty diesel vehicles need to meet the European Motor Vehicle Emissions Group (MVEG) cycle or U. S. Federal test procedure (FTP 75). Emissions that are monitored include hydrocarbon (HC), nitrogen oxides (NOx), carbon monoxide (CO) and total particulate matter (TPM). Low engine-exhaust temperatures (< 200°C during city driving) and high temperatures (> 500-800°C under full load and wide-open throttle) make emission control a formidable task for the catalyst designer Gas phase HC, CO and NOx reactions must be balanced with the removal of the soluble organic fraction for the vehicle to be in compliance with regulations. The SMART approach uses model gases under typical operating conditions in the laboratory to better understand the function of individual washcoat components.

Reduction of nitrogen oxides in Diesel exhaust gas is a challenging task. This paper reports results from an extensive study using Pt-based catalysts involving synthetic gas activity testing (SCAT), engine bench testing and tests on passenger cars. Preliminary SCAT work highlighted the importance of Pt-dispersion, and both SCAT and bench engine testing yielded comparable NOx conversions under steady state conditions at high HC:NOx ratios. On passenger cars in the European cycle without secondary fuel injection NOx conversion was lower than obtained in the steady state tests. Better conversion was obtained in the FTP cycle, where secondary injection was employed. Higher HC:NOx, ratios and more favourable temperature conditions which were present in the exhaust contributed to this higher conversion.

An overview is given on the state of the art of a new catalytic exhaust gas aftertreatment device for diesel engines. The function of a precious metal based, flow-through type diesel oxidation catalyst is explained. Much attention is paid to the durability of the diesel oxidation catalyst and especially to the influence of poisoning elements on the catalytic activity. Detailed data on the interaction of poisoning elements such as sulfur, zinc and phosphorus with the catalytic active sites are given. Finally it is demonstrated that it is possible to meet the stringent emission standards for diesel passenger cars in Europe with a new catalyst generation over 80.000 km AMA aging.

With the aid of a mathematical model the course of the reaction has been calculated for the system fuel additive / particulate trap; the effects of various additives were measured. The adjustment of a suitable regeneration system on a 1,6 liter turbocharged diesel engine is described, the effects on emission and wear is shown, an additive metering system is demonstrated.

Due to good trapping abilities, the ceramic trap filter was chosen for the reduction of the particulate emission of Diesel engines. Both, tests and the analysis of the regeneration kinetic show that in real-world application the lite-off limit of 500 °C may not be exceeded. The minimum exhaust gas temperature necessary for regeneration without the use of a catalyst, can be reduced to approx. 200 °C to 250 °C with the use of fuel additives. The use of additives for the filter regeneration showed excellent results in real-world conditions as well as with endurance tests. There was no significant change in emissions or specific fuel consumption about 20,000 km as compared to the operation without additives. The regeneration dependability however, is questionable because of the destruction of the filter.