Technical Paper
Development of Advanced Diesel Oxidation Catalysts
1999-12-01
1999-01-3075
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.
