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Increasingly stringent tailpipe emissions regulations have prompted renewed interest in catalyst heating technology – where an integrated device supplies supplemental heat to accelerate catalyst ‘light-off’. Bosch and Boysen, following a collaborative multi-year effort, have developed a Rapid Catalyst Heating System (RCH) for gasoline-fueled applications. The RCH system provides upwards of 25 kW of thermal power, greatly enhancing catalyst performance and robustness. Additional benefits include reduction of precious metal loading (versus a ‘PGM-only’ approach) and avoidance of near-engine catalyst placement (limiting the need for enrichment strategies). The following paper provides a technical overview of the Bosch/Boysen (BOB) Rapid Catalyst Heating system – including a detailed review of the system’s architecture, key performance characteristics, and the associated impact on vehicle-level emissions.

The present paper concentrates on the option of catalytic autothermal reforming of gasoline for fuel cell applications. Major parameters of this process are the “Steam to Carbon Ratio” S/C and the air to fuel ratio λ. Computations assuming thermodynamic equilibrium in the autothermal reactor outlet (ATR) were carried out to attain information about their proper choice, as failure in adjusting the parameters within narrow limits has severe consequences on the reforming process. In order to quantify velocity distribution just ahead the catalyst and to evaluate mixing uniformity we designed an ATR featuring an optical access: Thus flow visualization using PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) technique is possible. Preliminary PIV-results are presented and compared with CFD computations (Computational Fluid D ynamics).

The lower temperatures encountered with European Stage III/IV turbo charged direct injection (DI) Diesel engines with additional features such as cooled exhaust gas recirculation (EGR), compared to Stage II engines, means that modern light duty Diesel engine exhaust gas will rarely exceed temperatures of around 550° - 650°C under full load conditions, and under normal driving conditions, temperatures as low as 120°C will be common. The development of high activity Diesel oxidation catalysts (DOCs) having good low temperature performance is therefore key for achieving hydrocarbon (HC) and carbon monoxide (CO) conversions to meet Stage III and IV legislation. It is shown that extended operation of conventional DOC technology, at the lower temperatures encountered on modern Diesel engines, introduces an important mechanism of catalyst deactivation by accumulation of soot/coke and associated sulfur.

The study presented in this paper focuses on measures to minimize exhaust gas emissions to meet SULEV targets on a V6 engine by using a cost efficient system configuration. The study consists of three parts. A) In the first stage, the influence of engine management both on raw emissions and catalyst light off performance was optimized. B) Afterwards, the predefined high cell density catalyst system was tested on an engine test bench. In this stage, thermal data and engine out emissions were used for modeling and prediction of light-off performance for further optimized catalyst concepts. C) In the final stage of the program, the emission performance of the test matrix, including high cell density as well as multifunctional single substrate systems, are studied during the FTP cycle. The presented results show the approach to achieve SULEV emission compliance with innovative engine control strategies in combination with a cost effective metallic catalyst design.

The low exhaust gas temperatures experienced on light duty Diesel vehicles present a very challenging environment for the successful operation of catalytic aftertreatment. To meet the future more severe legislation, Diesel engines are being developed with greater combustion efficiencies and advanced fueling control. These engine developments may produce lower particulate matter (PM) and nitrogen oxides (NOx) emissions, but increased hydrocarbon (HC) and carbon monoxide (CO) emissions may occur. As a result of these engine changes exhaust gas temperatures may reduce still further. These factors demand catalysts with high oxidation activity at low temperatures. This paper reviews oxidation catalyst technology developed for light duty Diesel vehicles and the factors affecting their performance. Results obtained on synthetic gas rigs, bench engines and vehicles are presented. A discussion oh the effect of the level of sulfur (S) present in Diesel fuel on aftertreatment is given.

Meeting current exhaust emission standards requires rapid catalyst light-off. Closed-coupled catalysts are commonly used to reduce light-off time by minimizing exhaust heat loss between the engine and catalyst. However, this exhaust gas system design leads to a coupling of catalyst heating and engine operation. An engine-independent exhaust gas aftertreatment can be realized by combining a burner heated catalyst system (BHC) with an underfloor catalyst located far away from the engine. This paper describes some basic characteristics of such a BHC system and the results of fitting this system into a Volkswagen Touareg where a single catalyst was located about 1.8 m downstream of the engine. Nevertheless, it was possible to reach about 50% of the current European emission standard EU 4 without additional fuel consumption caused by the BHC system.

Misfiring of the engine can cause damage to the catalyst within short time and increase emissions. Under misfiring conditions, unburned fuel and oxygen are pumped into the catalyst, where its combustion heavily increases the temperature. For this reason there is a demand for fast detection of misfiring. Once judged, one can take countermeasures to avoid further temperature rise. Two methods of misfire detection with the prospect of future use in series production are discussed. A first approach uses the trace shape of the λ-sensor signal for evaluation. The second approach uses the speed fluctuations of the engine for detection. Efficient algorithms give the possibility of misfire detection in the full load-speed range with reasonable effort to protect the catalyst. However there will remain some misfire conditions, increasing the emissions above regulation limits, that cannot be detected by those methods.

As legislation tightens in the Heavy Duty Diesel (HDD) area it is essential to develop systems with high activity and excellent durability for both Particulate Matter (PM) and NOx control. The Continuously Regenerating Trap (CRT™) system controls hydrocarbon (HC), CO and PM emissions from HDD vehicles with efficiencies of over 90%, and has demonstrated very good field durability over distances exceeding 700,000 km. The system is widely used in Europe, and is demonstrating the same high performance and excellent durability within field applications in North America. The Continuously Regenerating Trap (CRT™) system has been developed and patented by Johnson Matthey [1]. Throughout this paper this system will be referred to as the Continuously Regenerating Diesel Particulate Filter, CR-DPF. The CR-DPF comprises an oxidation catalyst, optimised for NO2 generation from the engine-out NOx, and a downstream DPF.

Secondary air injection after cold start gives two effects for reduced exhaust emissions: An exothermic reaction at the hot exhaust valves occurs, which increases the temperature of the exhaust gas. It gives sufficient air to the catalyst during the cold start fuel enrichment that is necessary to prevent driveability problems. Handicaps for the wide use of air injection include space constraints, weight and price. An electrical air blower was choosen to best satisfy all these requirements. The development steps are described. The result is a three stage radialblower with extremly high revolutions of about 18000 rpm. The system configuration and the outcome are demonstrated on the new C-Class of Mercedes-Benz. The results show emission reductions higher than 50 %, while also satisfying the development goals of noise, volume, weight and cost requirements.

The tightening of Heavy Duty Diesel (HDD) emissions legislation throughout the world is leading to the development of emission control devices to enable HDD engines to meet the new standards. NOx and Particulate Matter (PM) are the key pollutants which these emission control systems need to address. Diesel Particulate Filters (DPFs) are already in use in significant numbers to control PM emissions from HDD vehicles, and Selective Catalytic Reduction (SCR) is a very promising technology to control NOx emissions. This paper describes the development and performance of the Compact SCR-Trap system - a pollution control device comprising a DPF-based system (the Continuously Regenerating Trap system) upstream of an SCR system. The system has been designed to be as easy to package as possible, by minimising the total volume of the system and by incorporating the SCR catalysts on annular substrates placed around the outside of the DPF-based system.