Cel
- Methods of catalytic conversion of nitrogen oxide in lean exhaust gas are on the threshold of usability. However, their efficiency is still far removed from that of the 3-way catalytic converter, and it is extremely questionable whether comparable efficiencies will ever be reached.
- Highly active noble-metal catalysts such as are required for the low exhaust-gas temperature level of Diesel cars permit a maximum of 25% NOx conversion in the operating range described by the MVEG test. Formation of undesirable byproducts, like N2O and NO2 is an additional criterion for the further development of these catalyst types.
- High- and low-temperature catalyst combinations allow conversion rates up to approximately 40% in truck engines in the R49 test, and 20 to 25% in lean-burn spark-ignition engines in the MVEG test.
- For engines which have to be run under stoichiometric or rich conditions for periods of time (lean mix engines), only noble metal-based lean catalysts are usable, because zeolite catalysts with transition metals are not resistant to ageing. Exhaust hydrocarbons from lean gasoline engines are well suited as reducing agents. Additional injection of reducing agent is not necessary.
- Research in this field must be identified in order to be able to achieve the objectives of reduced consumption and CO2 reduction with simultaneous reduction of nitrogen oxide emissions.
Processes and catalyst materials for the reduction of nitrogen oxides in net oxidizing exhaust atmosphere shall be examined.
As reducing agent hydrocarbons as well as nitrogen containing components shall be used.
Basic investigations, an intensive catalyst screening, and application oriented systems work will be performed.
The application of processes and catalysts on diesel engines of IDI and DI-type and on lean otto engines will be investigated.