(a) Oven characteristics.
The oven used for termally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000 ±10 °C.
(b) Evaluation gas composition.
(1)
A synthetic exhaust gas mixture is used for evaluating the effect of thermal stress on catalyst conversion efficiency.
(2)
The synthetic exhaust gas mixture must have the following composition:
Carbon Monoxide 1
|
1 |
|
Oxygen |
1.3 |
|
Carbon Dioxide |
9 |
|
Water Vapor |
10 |
|
Sulfur Dioxide |
|
20 |
Oxides of Nitrogen |
|
280 |
Hydrogen |
|
3500 |
Hydrocarbon 1,2
|
|
4000 |
Nitrogen=Balance |
|
|
1 Alternatively, the carbon monoxide and hydrocarbon proportions of the mixture may be changed to 1.2% and 4650 ppm, respectively (using on of these alternative concentrations requires that the other be used simultaneously). |
2 Propylene/propane ratio=2/1. |
Code of Federal Regulations
[61 FR 52102, Oct. 4, 1996; 62 FR 20066, Apr. 24, 1997]