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Future emission legislation can be met through substantial improvement in the effectiveness of the exhaust gas after-treatment system, the engine and the engine management system. For the catalytic converter, differentiation is necessary between the cold start behavior and the effectiveness at operating temperature. To be catalytically effective, a converter must be heated by the exhaust gas up to its light-off temperature. The major influential parameter for the light-off still is the supply of heat from the exhaust gas. Modification of the cold start calibration of engine control such as spark retard or increased idle speed can increase the temperature level of the exhaust gas. One further possibility is represented by a reduction of the critical mass ahead of the catalyst (exhaust manifold and pipe). Nevertheless the best measure to obtain optimal cold start effectiveness still seems to be locating the converter close to the engine.

A particulate trap with combined regeneration has been developed for use in light duty vehicles with diesel engines. This new system was tested first on an engine test rig. On-road vehicle tests are going on since August 1998. The results obtained clearly demonstrate the feasibility of this system. With this system trap regeneration has to be ensured under worst case conditions (exhaust gas temperature<400° C). To meet this requirement electrical heating in combination with a fuel-borne catalyst is applied. Different filter materials such as cordierite wall flow and silicon carbide monoliths were tested on the engine test rig. The paper reports on results from the engine test rig as well as from on-road vehicle testing. An overview about pre-heating and regeneration examples are given and energy balances are presented.

Emissions during the useage phase of vehicles are of increasing interest in environmental protection, and consequently, there is considerable interest in exhaust systems. The automotive exhaust system including the catalytic converter is, because of the precious metals in the catalyst, of particular interest for the recycling of automotive parts. The paper will describe the recycling technology of ceramic and metal catalyst substrates. The process will be analyzed in detail with the example of metal supports. As a result the complete life cycle and the recycling efficiency are presented.

Against the background of the current discussions on the reduction in CO2 emissions, the development of lean-burn engines is acquiring increasing importance. In order to meet future emissions limits, new strategies are required, especially for NOx conversion. One technique developed in recent years for the conversion of NOx in lean exhaust gases is the NOx adsorber catalyst, which stores NOx in lean operating conditions and must periodically be regenerated with rich exhaust gas. In this paper, the influence of catalyst substrate design on NOx conversion is described. In addition NOx conversion measurements with NOx adsorbers of various cell densities, variable diameter/length ratios as well as smooth and structured channel walls are carried out.

Exhaust after-treatment systems will have to become increasingly efficient in order to comply with the strict emission limits that will apply in the European Union and worldwide in future. Moreover, space constraints, weight and low pressure drop are just some of the issues that have to be addressed by an EU III-compliant catalytic system. The development of metallic substrates over the past few years has shown that turbulent-like substrates increase specific catalytic efficiency. This has made it possible to enhance overall performance for a specific catalytic volume or reduce the volume while keeping catalytic efficiency constant. This paper focuses on the emission efficiency of standard, TS and PE metallic substrates. A simulation tool and flow bench measurements were used to develop a test matrix with catalyst similar pressure drop in order to examine different cell densities, substrate lengths and coating technologies.