Technical Paper
Laboratory Screening of Diesel Oxidation Catalysts and Validation with Vehicle Testing: The Importance of Hydrocarbon Storage
1996-10-01
962049
A laboratory flow reactor test has been developed to examine hydrocarbon (HC) storage for diesel catalysts. Light-off testing alone has not been sufficient to rank diesel oxidation catalysts (DOCs) in agreement with vehicle HC conversions over the European driving cycle. HC emissions are important because of Stage II combined HC+NOx standard. During cold start and much of the ECE driving cycle, inlet catalyst temperatures on diesel passenger cars spend much time below 200°C. This is where more than half of the HC mass can be emitted. To be effective, DOCs must achieve sufficiently low HC light-off temperatures, or incorporate materials such as zeolites that trap HC until light-off is achieved. Consideration of both HC storage and light-off results together improve ranking of DOCs similar to vehicle ranking. Three supplier DOCs have been evaluated.
