Nitrogen Dioxide in Engine Exhaust

Nitrogen dioxide emissions from diesel and gasoline internal combustion engines have been measured over a range of speed, load and AFR conditions.

Measured NO₂ levels are very much higher than expected thermodynamically, with as much as 30% of the NO_x emission from a diesel engine at 15% load in the form of NO₂.

Stainless steel surfaces, platinum and copper chromite catalysts, when in the temperature range 400 ⇥ 500°C have been shown to oxidise NO to NO₂ provided the CO concentration in the exhaust gas is below 0.1%.

Analytical techniques and methods of removing NO₂ have been considered.