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Diesel engine emission regulations throughout the world have progressed over the last 20 years. In the U.S. the most stringent medium/heavy duty standard will be implemented for on highway vehicles starting in 2010. Although changes to engine design will improve engine out emissions, in order to meet both PM and NOx regulations, combination systems including PM and NOx aftertreatment, are planned to be utilized. In order to achieve the required regulations, a new substrate technology has been developed using advanced “turbulent” flow characteristics, and it has been combined with a novel approach to reduce system complexity: the “SCRi™” or “SCR integrated” system. Such a system uses a continuously operating PM-Metalit with advanced “turbulent” SCR-catalysts in a unique configuration. The reduction of both PM and NOx also has to be seen in context with its effect on CO2 emissions.

Emission legislations for the light / medium and heavy duty vehicles are becoming more and more stringent worldwide. Tightening of NOx and Particulate Matter (PM) limits further from Euro III to Euro IV levels has provoked the need of either controlling NOx from the engine measures and use PM control after-treatment devices such as Partial Flow Filters, or, controlling PM from the engine measures and use NOx control devices such as Selective Catalytic Reduction (SCR) systems. Manufacturers have adopted different strategies, depending upon the suitability, cost factors, infrastructure development and ease of maintenance of these systems. PM Metalit®, is a partial flow filter, which captures particulates coming out of the exhaust and re-generates on a continuous basis with the help of Nitrogen Dioxide (NO2) in the exhaust.

1 An experimental study has been carried out on a production vehicle by means of roller-bench emission tests in order to optimize alternative aftertreatment systems. To this aim different comparisons between the production exhaust system and new strategies are discussed in the present paper with aid of both modal emission data and bag tailpipe figures. The present work shows the application of a alternative solution that complies with future emission legislation with regard both to HC, CO, NOx and PM without any major engine power output or fuel consumption penalty.

In order to achieve ultra low emission levels with three-way catalysts, an early accurate air/fuel ratio control is essential. Positioning the oxygen sensor in the first part of the substrate helps to protect the oxygen sensor from being splashed by water during cold start, so that early heating and activation becomes a less limiting factor. For emission control purpose, a position of a rear sensor in the warm part of the catalyst gives improved possibilities for oxygen buffer control during catalyst warming up conditions. This enhances balancing HC and NOx in an early phase. In addition, for OBD reasons it is possible to locate the sensor in any axial position in the catalyst, which improves design possibilities for cold start detection, even for single brick catalyst systems. The paper describes the construction of the catalyst with an integrated oxygen sensor.

On one hand, latest worldwide emissions legislation developments aim to reduce NOx and Particulate Matter (PM) emissions of all diesel engines, while on the other hand lower fuel consumption diesel engines are still required for lower fleet average CO₂ emissions. As a consequence of the chosen CO₂ optimized combustion mode, the raw NOx emission increases and as such Selective Catalytic Reduction (SCR) technology will be the future choice for high efficiency NOx aftertreatment. This paper deals with SCR technology and its derivative SCRi® technology, when diesel particle reduction is required, especially for heavy-duty applications. Alongside the developed metal catalyst technologies, a complete SCR reducing agent dosing system is presented. Emission results gained with the SCR or SCRi® technologies on European commercial engines illustrate the potential of these technologies for conversion of NOx and PM emissions.

More efficient and durable catalytic converters for the two- and three-wheeler industry in developing countries are required at an affordable cost to reduce vehicle emissions, to maintain them at a low level and therefore to participate in a cleaner and healthier environment. This particularly is true nowadays, because the demand and prices of Platinum Group Metal (PGM) for catalyst are continuously increasing due to i) the worldwide progressive implementation of motorcycles emission legislations similar to Euro 3 Stage requiring catalysts, ii) the need for non-road diesel vehicles to be equipped now with catalyst systems, and iii) the constant increase of the worldwide automobile market. A new generation of metallic substrates with structured foils for catalytic converters is proven to be capable of improving conversion behavior, even with smaller catalyst size.

The Selective Catalytic Reduction (SCR) is the main after-treatment solution for high efficient diesel engines under development to cope with future lower fuel consumption and NOx emissions requirements (EU6+ legislation). Exhaust gas temperatures are decreasing too, leading to new after-treatment system developments in a close coupled position. Nevertheless before all vehicle architectures allow it, SCR systems are and will still be installed in underbody position. The current paper deals with an underbody metal SCR after-treatment systems, which is capable of active thermal management, and an ultra-compact SCR dosing system. These technologies are described and emission results obtained on several application examples (from passenger cars to light duty commercial vehicles) are presented and discussed in conjunction with an effective active thermal management of the SCR function.

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.