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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.

The Natural Gas Vehicle (NGV) Challenge '92, was organized by Argonne National Laboratory. The main sponsors were the U.S. Department of Energy the Energy, Mines, and Resources - Canada, and the Society of Automotive Engineers. It resulted in 20 varied approaches to the conversion of a gasoline-fueled, spark ignited, internal combustion engine to dedicated natural gas use. Starting with a GMC Sierra 2500 pickup truck donated by General Motors, teams of college and university student engineers worked to optimize Chevrolet V-8 engines operating on natural gas for improved emissions, fuel economy, performance, and advanced design features. This paper focuses on the results of the emission event, and compares engine mechanical configurations, engine management systems, catalyst configurations and locations, and approaches to fuel control and the relationship of these parameters to engine out and tailpipe emissions of regulated exhaust constituents.