1994-03-01

Optimization of Extruded Electrically Heated Catalysts 940468

Low mass extruded electrically heated catalysts (EHC) followed directly by light-off and main converters resulted in non-methane hydrocarbon emissions (NMHC) between .020 and .023 g/mi at power levels as low as 1 kw and energy levels as low as 4 whr. These results were achieved on a 1993, 2.2 liter vehicle. The success of this system is due to rapid heat up of the catalyzed surface areas of both the heater and light-off converter. The energy added to the exhaust from both the heater and the light-off is then efficiently transferred to the main converter.
In addition, the impact of power and energy on NMHC levels was determined. The Ultra-Low Emissions Vehicle (ULEV) standard was also achieved with uncatalyzed heaters and on a 1990, 3.8 L vehicle.
The new California Low Emission Vehicle (LEV) and Ultra Low Emission Vehicle (ULEV) standards require a significant reduction in tail pipe emissions compared to current standards. One of the biggest challenges is achieving the non-methane organic gases (NMOG) level for the LEV and ULEV standards. Many strategies have been studied to achieve lower cold start tail pipe hydrocarbon emissions such as electrically heated catalysts (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and 18), hydrocarbon storage devices (19,20), light-off converters (21), and exhaust gas ignitors (22). Electrically heated catalysts have received the most attention and have been demonstrated to be an effective solution. Previous EHC systems yielded low emissions but they required unacceptably high power and energy. Corning's development efforts have been focused on continuing to achieve low emissions while significantly lowering power and energy. This paper will discuss the development of new EHCs and systems which operate at significantly lower power and energy levels.

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