Electrically Heated Metal Substrate Durability

Emission performance of an electrically heated catalytic converter is presented for both low-mileage tests and after exhaust aging using a 300 h dynamometer schedule. The aged converter system maintained its ability to significantly reduce cold start hydrocarbon and CO emissions on a late model gasoline-fueled passenger car. In these tests HC and CO emissions were reduced by 76% and 92%, respectively, during the first 140 seconds of the FTP urban driving cycle by operating the aged converter with resistance heating and air injection, in comparison to operation of the same aged converter in an unheated configuration. These reductions for heated operation versus unheated operation were comparable to the 80% HC and 96% CO cold start emission reductions observed in low-mileage testing of the same converter. The air injection strategy used in the resistively heated operation increased cold start NO_x emissions in the first 140 s of the FTP by 60% versus unheated operation of the low-mileage converter. After engine aging, the converter exhibited similar NO_x performance in the cold start phase for both heated and unheated operation. No changes in heat-up performance were observed for the heated catalyst after the aging protocol or after hot vibration testing using a 760°C inlet engine exhaust temperature.