The Influence of Oxidation Catalysts on NO2 in Diesel Exhaust 932494
In underground noncoal mines the emission of nitrogen dioxide (NO2) in the exhaust of a diesel engine is more important than the emission of nitrogen oxide (NO) because of the much lower permissible exposure limit for NO2. Consequently, the tendency of aftertreatment devices such as oxidation catalytic converters (OCCs) to oxidize NO to NO2 is counterproductive.
The U.S. Bureau of Mines (USBM) is investigating the effects of OCCs upon NO2 emission by using a Fourier Transform Infrared (FTIR) exhaust gas analyzer to compare the concentration of NO2 in diesel exhaust upstream and downstream of the OCC. We find that some OCCs increase the concentration of NO2 much more than others, and that over some temperature ranges the aftertreatment results in an apparent decrease in NO2 concentration.