Due to the high percentage of NOX emissions generated by mobile vehicles, current and future legislation for NOX limits is of especially high importance for the automotive industry. In Europe those include not only the more stringent yearly averaged level for inner city NO2 emissions, but also a proposal of the EU parliament of a NOX limitation value for EU 6 legislation of 80 mg/km for passenger cars. In addition, a proposition of the EU commission for a NOX limitation value for Stage VI for heavy duty trucks of 400 mg/kWh is being discussed. In the US the requirements with US BIN 5 for passenger cars and US2010 for Heavy Duty Trucks are comparable.
There is no doubt about the necessity of the usage of exhaust after treatment systems for NOX reduction in order to fulfil these requirements, however largely unclear are the technical details of systems capable to fulfil these requirements. Those usually are implemented into an area of conflict between costs, efficiency, space requirements, and fuel consumption/CO2 emissions.
In this paper, special attention will be paid to the SCR-System consisting of the dosage and catalyst system. In addition it will be examined, which catalyst design and structure has a particular attribute regarding the target values costs, space, back-pressure and efficiency. Examinations on a synthetic gas reactor, motor test bench and the roller test bench were executed to define a SCR- System based on the metal substrates.