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The combustion efficiencies of diesel oxidation catalysts (DOC) targeted for use in the heat-up role of active diesel particulate filter (DPF) systems are investigated. Light-off tests using synthetic gases and fuel injection studies on light and heavy duty engines, both before and after thermal aging, are carried out. These evaluations are used to demonstrate differences in activity between closely related Pt-only and Pt/Pd formulations. Post-mortem analyses are conducted to determine the basis for the performance differences observed during the fuel injection studies. These analyses include measurement of the accumulation of carbonaceous compounds on catalyst surfaces which are associated with incomplete combustion of the injected fuel. Aging cycles developed for DOC+DPF systems incorporating heat-up by in-exhaust fuel injection on heavy-duty diesel engines are presented. The impact of these aging cycles on the performance of a Pt/Pd catalyst are summarized.

This paper describes the results of a joint development program focussing on the introduction of the new generation of Pt/Rh-technology for current and future emission standards as a cost effective alternative to the in serial Pd/Rh based exhaust gas concepts. In the initial phase of the program combinations of Pd- and Pt-based three-way catalyst technologies were evaluated on vehicles equipped with a 8 cylinder engine. One goal in this portion of the study was to achieve technical equivalence between a viable Pd-based technology and the new Pt/Rh technology in the underfloor position at lower precious metal loading. A combination of a close-coupled Pd/Rh technology and the new Pt/Rh in the underfloor position was able to meet the emission targets at significant lower costs of the system after a catalyst aging that resembles more than 100.000 km of vehicle German highway driving.

The future emission limits for gasoline fuelled passenger cars require more and more efficient exhaust gas aftertreatment devices - the catalytic converter being one essential part of the complex system design. The present paper summarizes the results of several basic research programs putting major emphasis on the application of highly sophisticated three-way catalyst technologies being taylored for the utilization on ultra thin-wall ceramic substrates. In the first part of the investigation the following effects were examined in detail: Different washcoat loadings at constant PGM-loadings Different volumes of catalysts for constant amounts of PGM and washcoat Similar washcoat technologies at different ratios of WC-loading to precious metal concentration in the washcoat.

World over, emission legislations are becoming stringent day by day. India too, is on the road map for more tough emission legislations. 2/3 Wheeler legislations in India are being considered as the most stringent in the world, where as, Passenger Car and light/heavy duty legislations are reaching Euro III and Euro IV limits in the near future. The present paper describes the system concepts to be followed to reach the emission targets, specially for Euro III and Euro IV for passenger cars. That includes necessity for using more advanced engine technologies such as Turbo Charging with Intercooling, EGR (cooled), Electronically Controlled Direct Injection, Common Rail / Pump - Nozzle systems. The new catalyst technologies required and developed for these applications are described. These technologies not only require to offer efficient emission reduction under fresh conditions, but need to meet the targeted results after long aging of over 80,000 km. The paper is divided in two parts.

World over, emission legislations are becoming stringent day by day. India too, is on the road map for more tough emission legislations. 2/3 Wheeler legislations in India are being considered as the most stringent in the world, where as, Passenger Car and light/heavy duty legislations are reaching Euro III and Euro IV limits in the near future. The present paper describes the system concepts to be followed to reach the emission targets, specially for Euro III and Euro IV for passenger cars. That includes necessity for using more advanced engine technologies such as Turbo Charging with Intercooling, EGR (cooled), Electronically Controlled Direct Injection, Common Rail / Pump - Nozzle systems. The new catalyst technologies required and developed for these applications are described. These technologies not only require to offer efficient emission reduction under fresh conditions, but need to meet the targeted results after long aging of over 80,000 km. The paper is divided in two parts.

The following paper highlights the results of a vehicle emission improvement program with emphasis on two main points: In the initial phase, various combinations of Pd and Pt-based three-way catalyst technologies were evaluated on a TLEV and a LEV calibrated vehicle in order to generate ULEV exhaust gas levels. One goal in this portion of the study was to achieve technical equivalence between a viable Pd-based technology and a newly developed Pt-based technology. A combination of the Pd- and Pt-based technologies was able to meet the ULEV and part of the ULEV II regulations in the test vehicle after a catalyst aging cycle that resembles 50,000 miles of vehicle driving. In the later phase, a mathematical algorithm based on the original TLEV and LEV vehicle data was developed in order to conduct computer modeling of the exhaust gas aftertreatment system. This algorithm described the kinetic behavior of the individual catalysts over a broad range of reaction conditions.

The present paper highlights the results of a development program focussing on Pt-based three-way catalysts. It is demonstrated that as compared to state-of-the-art Pt/Rh technologies the utilization of advanced washcoat raw materials, new processing methods as well as advanced washcoat systems dedicated to the individual precious metals (PGM) lead to novel catalyst technologies taking better advantage of the lead to novel catalyst technologies taking better advantage of the PGM properties. This yields substantial improvements regarding both aging stability and activity of the catalytic converters. Furthermore, based on the results of a PGM loading study, preferred PGM loadings and ratios were investigated in more detail. In summary, for different application examples it is documented that the newly developed Pt/Rh double layer catalyst is a technical and commercial alternative to the current Pd-based technologies also for high-demanding applications.

The present paper describes the results of a joint development program focussing on a system approach to meet the EURO IV emission standards for an upper class passenger car equipped with a newly developed high displacement gasoline engine. Based on the well known catalyst systems of recent V6- and V8-engines for the EURO III emission standards with a combination of close coupled catalysts and underfloor catalysts, the specific boundary conditions of an engine with an even larger engine displacement had to be considered. These boundary conditions consist of the space requirements in the engine compartment, the power/torque requirements and the cost requirements for the complete aftertreatment system. Theoretical studies and computer modeling showed essential improvements in catalyst performance by introducing thin wall substrates with low thermal inertia as well as high cell densities with increased geometric surface area.

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.

In order to meet recent and future stringent hydrocarbon emission regulations of passenger cars, the use of Pd-containing catalysts is of growing interest. This is especially true for Pd/Rh and Pt/Pd/Rh catalysts. To optimize the function of the individual precious metals, most high-performance catalysts have a double layer configuration. This double layer avoids undesired interactions between Pd and Rh after reacting with exhaust gas at a high temperature level. Of course, these double layer technologies lead to a more complex capacity utilization coating process during the manufacture of the catalyst. The present work summarizes the results of a research program targeting the development of a high-performance single layer Pd/Rh catalyst technology. The starting point was the functional improvement of Pd and Rh only catalysts then subsequently combining the best of these technologies.

The present paper describes the results of a joint development program focussing on a system approach to meet the proposed EURO III and IV emission standards for a passenger car equipped with a 3.2 liter, 18 valve gasoline engine. Starting with the in-production configuration of a EURO II certified vehicle (model year 1997) the following improvement points were investigated in detail. By the introduction of a close-coupled catalyst in combination with engine measures to improve the catalyst light-off the proposed EURO III limits were met. The proposed EURO IV hurdle could be overcome by further using secondary air injection during cold-start in combination with an increased precious metal loading for the close-coupled catalyst.