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In urban areas, particulate emission from Diesel engines is one of the pollutants of most concern. As a result, particulate emission control from urban bus Diesel engines using particulate filter technology is being introducing in La Rochelle. The Diesel Particulate Filter (DPF) introduction on the existing urban bus fleet has been initiated by the CDA La Rochelle through a voluntary retrofit program. The class of urban bus to be retrofitted is based on EURO 1 and EURO 2 Diesel engines, using a standard European Diesel fuel with 300ppm of Sulphur content. In that case, the appropriated technology for DPF regeneration requires a very flexible strategy for DPF regeneration, such as the use of the Ceria-based Fuel-Borne Catalysts. The paper describes the practical approach developed to install and optimize the DPF System on the urban buses.

A novel method for the evaluation of fuel-borne catalysts effect on DPF regeneration temperature is presented. The method is simple and allows for the in-situ determination of the regeneration temperature. It consists of the engine and trap preconditioning, the trap loading cycle and the regeneration phase. The repeatability of the method is better than ±1% of average value measured. The method is capable of distinguishing very low concentrations of the metal catalyst. The application of the method with different concentrations of the same catalyst does not require the use of fresh traps. For the evaluation of different catalysts however it is recommended to use a fresh trap, since the prescribed preconditioning is not capable of eliminating the effects of the previous additive.

In May 2000, PSA Peugeot Citroën launched, the Peugeot 607 HDi (High pressure Direct Injection) luxury sedan, the first series-production diesel passenger vehicle equipped with a Diesel Particulate Filter (DPF). The elimination of diesel particulate emissions is achieved by sequential trapping followed by regeneration of the DPF, assisted by a Ceria-based Fuel-Borne Catalyst (Ceria-FBC). In order to ensure reliable and durable DPF regeneration under all driving conditions, including the most demanding such as prolonged periods of idling and low speed driving, active and integrated system approaches are used. This technology was subsequently transferred to the diesel versions of the Peugeot 406 and the newly-launched Peugeot 307 and Citroën C5. This paper presents the functional and technical characteristics of the Ceria-FBC to fulfil specification requirements.

Since the market introduction of the Diesel Particle Filter (DPF) system in serial applications in May 2000, more than 500,000 vehicles have been DPF-equipped. Tracking the serial production current situation, several themes for improvement have been identified, including system simplification to limit its total cost as well as proposition to optimize maintenance. The paper presents those upgrades that will be proposed in serial applications. Based on a DPF regeneration assisted by engine management systems in combination with the use of a Ceria-based fuel-borne catalyst, the first improvement is to limit the ash build up phenomenon of fuel-borne catalyst and then to limit the DPF clogging effect. In the first stage, catalytic activity of Ceria-based fuel-borne catalyst has been improved, by introducing Iron as a catalytic promoter.