Search Results

Several diesel powered passenger car manufacturers in the European Union announced recently the future use of catalysed diesel particulate filter systems on their vehicles. The filtration of the exhaust gas is being worked on since several years. Different filter materials and filter designs proved their ability to achieve high filtration efficiencies over the lifetime of the vehicle. The major technological challenge is the periodic regeneration of the filters loaded with the retained diesel particulates. In order to promote filter regeneration, catalytic activation of the accumulated soot is advantageous. Therefore, the first serial application of diesel particulate filter system (diesel oxidation catalyst combined with an uncoated filter substrate) uses catalytically active fuel additives. These systems have been introduced about four years ago and proved to be a viable technology to clean the exhaust gas of passenger car diesel engines.

India, as a major two and three wheeler production center in the world, is also leading with the stringent emission regulations for this segment of the vehicles. Emission legislations were introduced in 1991 and have been progressively tightened since 1996. The present legislations of 2.0 g/km CO, 2.0 g/km HC+ NOx for two wheelers and 4.0 g/km CO, 2.0 g/km HC+NOx for three wheelers, are being considered as the most stringent in the world. In addition, a voluntary emission warranty of 30,000 km by the manufacturers of two and three wheelers and a deterioration factor of 1.2 on the emission norms of the catalyst equipped vehicles, put an additional strain on the catalyst technologies, as well as on the overall vehicle systems. In order to meet these challenges, and with focus on the cost effective solutions required for developing countries like India, new advanced catalyst technologies have been developed with improved performance and even lower precious metal content.

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 exhaust emissions of two and three wheelers contribute to a major extent to the pollution in urban areas of South East Asia and especially India. Most of this class of vehicles are equipped with 2 stroke engines, which operate constantly rich, - leading to high carbon monoxide and hydrocarbon emissions. On the other hand the NOx concentration in the exhaust gas is neglegible. In near future more stringent exhaust gas legislation get effective in a number of countries. Therefore catalytic aftertreatment devices are necessary to meet the emissions limits. Hot Tubes™ and/or monolith type catalysts can be applied. The high exhaust gas hydrocarbon concentrations lead to high exotherms on oxidation which drives the exhaust gas temperatures up to a range between 750 and 850°C. Therefore thermal ageing of the Hot Tubes™ and monolith type catalysts is severe. The design of advanced catalyst systems has to take this into account.

The exhaust emissions of two stroke vehicles like motorbikes and scooters contribute to the pollution in urban areas of developing countries in South East Asia and India to a major extent. But also in Japan and selected European countries exhaust gas limitations become effective from 10/1998 and 06/1999 for these vehicles. To control this emissions catalytic aftertreatment by Hot Tubes® and/or monolith type catalysts are applied. Due to the constant rich operation of the two-stroke engines, common design criteria for three-way catalysts fail. Extremely high exhaust gas hydrocarbon concentrations lead to high exotherms during oxidation which increases the exhaust gas temperature to a range between 800 and 900 °C. Furthermore the lack of oxygen limits the CO and HC oxidation under certain engine operation conditions. Therefore, water-gas shift and steam reforming reactions play an important part in catalytic aftertreatment of two-stroke exhausts.

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.