Technical Paper
Air Injection to an Electrically-Heated Catalyst for Reducing Cold-Start Benzene Emissions from Gasoline Vehicles
1990-10-01
902115
This paper describes the laboratory effort to determine the emissions benefit of cold-start air injection to a preheated automotive catalyst. Previous experimentation with an electrically-heated catalyst on a gasoline-fueled vehicle with no supplemental air showed little improvement in hydrocarbon emission control. In this study, air was injected ahead of an electrically-heated catalyst during cold-start operation. Analysis of continuously recorded raw exhaust emissions were used to determine air injection calibrations and oxidation-reduction trade-offs. Improved control of non-methane hydrocarbons (NMHC), benzene, and carbon monoxide (CO) emissions was observed. Nitrogen oxides (NOx) emission control was maintained by the use of a carefully controlled air injection flow-rate and schedule. This study determined that heating an auto-motive exhaust emission catalyst prior to cold-start operation may not be sufficient in itself.