Status Report on HC/CO Oxidation Catalysts for Exhaust Emission Control Mobil Research and Development Corporation

Format:

Conference/Event

Author/Creator:

Snyder, P. W., author.

Conference Name:

National Automobile Engineering Meeting (1972-05-22 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 1972

Summary:

The 1975 federal CVS test procedure and emission standards have placed a heavy emphasis on minimizing the time required after engine start up to begin converting exhaust emissions. Four major improvements in catalytic HC/CO converters have been made in the past year to reduce catalyst ignition time:Small laboratory samples of potential HC/CO oxidation catalysts were screened for activity in a "laboratory simulated cold-start" test with exhaust from a 2-cyl engine. Several improved catalyst candidates were evaluated in a full-size converter "cold-start" test with exhaust from a 351 in3 engine.Locating the converters closer to the exhaust manifold results in higher catalyst operating temperatures which require greater stability at high temperatures in the presence of trace contaminants. Stability, when exposed to wide temperature variations and changes from oxidation to reduction environments, has been evaluated in a thermal-cycling test for several improved catalysts. Catalyst stability to long-term exposure has also been evaluated in an engine dynamometer mileage accumulation test operated under simulated road conditions.Unfortunately, the rapid thermal-chemical response of the improved catalyst, operated closer to the exhaust manifold, increases the occurrences of excessive catalyst temperatures. Mathematical model studies of the effect of the improved catalyst properties on thermal response indicate a need to prevent unexpected high CO or HC concentration peaks in the engine exhaust, or to improve properties of existing catalysts. System changes, such as moving the low temperature catalyst farther from the exhaust manifold, may be required to obtain some protection from catalyst overtemperatures. These changes increase emission levels and require a breakthrough in engine control of raw emissions or improved catalysts

Notes:

Vendor supplied data

Publisher Number:

720479

Access Restriction:

Restricted for use by site license