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Successful system integration of NOx storage catalyst properties into engine management functions implies a profound understanding of the catalyst's performance under transient exhaust gas conditions. During lean operating conditions, this technology achieves a high level of NOx conversion by storing nitrogen oxides reversibly as nitrates. Periodically, the engine control induces a switch to rich, i.e. to reducing conditions, leading to a regeneration of the NOx storage component. The present paper focuses on the investigations of the NOx storage as well as the regeneration process under the described transient reaction conditions for gasoline lean burn applications. In order to study the influence of NOx mass, of the amount of reduction agent offered and of specific regeneration components, experiments were conducted by means of heated exhaust gas oxygen (HEGO) sensors on a model gas as well as an engine test bench.

To support the application and design of exhaust gas aftertreatment systems for gasoline fueled passenger cars based on hydrocarbon adsorber catalysts, a computer model was developed. This model is based on simplified, lumped kinetics for the adsorption and desorption of hydrocarbons and for the oxidation of CO and hydrocarbons. Also included in the model are convective transport of heat and mass in the gas phase, mass and heat transfer to the washcoat layer, and diffusion with reaction in the washcoat layer. The continuity equations for this model with the appropriate boundary conditions were solved for a single channel assuming adiabatic behavior. After validation of the prediction on experimental results, this model was used to perform a simple parametric study on the influence of inlet temperature,CO concentration, washcoat loading, adsorber content, and cell density on the HC emission.

Zirconium dioxide (zirconia) is a well-known material often being a major component in the washcoat systems of three-way catalysts (TWC) and diesel oxidation catalysts. One important characteristic of zirconia containing washcoats is an improved aging stability which is required to meet the more and more stringent emission standards. In the last few years the utilization of zirconia became even more important - especially for high sophisticated three-way washcoat systems. This was due to the development of high temperature stable oxygen storage components, containing cerium dioxide (ceria) in combination with different other oxides - one very promising candidate being zirconia. In the present work the results of a research program are discussed, focusing on the influence of zirconia in combination with ceria and additional rare earth promoters on the stability of the oxygen storage characteristics.

Catalyst applications for gasoline and diesel engine powered passenger cars and 2-stroke Two- and Three-wheelers are the main focus of this paper. Catalyst durability and deactivating effects are discussed in detail. Experiences on Indian conditions are also included.

The performance of two catalyst preparations, styled base and base/noble, were determined employing a simulated mining vehicle loading cycle. Such cycles are characterized by sufficiently high exhaust temperatures to cause auto-regeneration of the filter units when these catalyst preparations are employed. Such loading is exhibited in raining service by some moderate and most high production load-haul-dump vehicles plus some haulage trucks. These preparations were shown to be capable of depressing the nominal, ‘untreated’ steady-state minimum soot ignition temperature of approximately 500°C (932°F), to a range varying from 395°C to 424°C (743°F to 797°F). Results of gaseous constituent analyses, particulate determinations, polynuclear aromatic hydrocarbon sampling, catalytic sulphur conversion (SO2 to H2SO4) and Ames testing are presented for the two catalyst preparations studied.