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The term NO x represents several forms of nitrogen oxides such as NO (nitric oxide), NO 2 (nitrogen dioxide) and N 2 O (nitrous oxide, also known as laughing gas).In a gasoline engine, NO is the most common form of NO x at around 93%, while NO 2 is around 5% and the rest is N 2 O.
In atmospheric chemistry, NO x is shorthand for nitric oxide (NO) and nitrogen dioxide (NO 2), the nitrogen oxides that are most relevant for air pollution. [ 1 ] [ 2 ] These gases contribute to the formation of smog and acid rain , as well as affecting tropospheric ozone .
EGR valve the top of box on top of the inlet manifold of a Saab H engine in a 1987 Saab 90. In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NO x) emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. [1]
Ammonia, in the presence of oxygen and a catalyst, reduces two different nitrogen oxides: [14] 4 NO + 4 NH 3 + O 2 → 4 N 2 + 6 H 2 O ("standard SCR") and 6 NO 2 + 8 NH 3 → 7 N 2 + 12 H 2 O ("NO 2 SCR selective catalytic reduction") [citation needed] NO + NO 2 + 2 NH 3 → 2 N 2 + 3 H 2 O ("fast SCR") The overall reduction of NO x by urea is ...
A NO x adsorber is designed to reduce oxides of nitrogen emitted in the exhaust gas of a lean burn internal combustion engine.Lean burn engines, particularly diesels, present a special challenge to emission control system designers because of the relatively high levels of O 2 (atmospheric oxygen) in the exhaust gas.
An exhaust pipe must be carefully designed to carry toxic and noxious gases away from the users of the machine. Indoor generators and furnaces can quickly fill an enclosed space with poisonous exhaust gases such as hydrocarbons, carbon monoxide and nitrogen oxides, if they are not properly vented to the outdoors. Also, the gases from most ...
Selective catalytic reduction (SCR) means converting nitrogen oxides, also referred to as NO x with the aid of a catalyst into diatomic nitrogen (N 2), and water (H 2 O). A reductant, typically anhydrous ammonia (NH 3), aqueous ammonia (NH 4 OH), or a urea (CO(NH 2) 2) solution, is added to a stream of flue or exhaust gas and is reacted onto a ...
[not verified in body] While total nitrogen oxides from petrol cars have decreased by around 96% through the adoption of exhaust catalytic converters as of 2012, diesel cars still produce nitrogen oxides at a similar level to those bought 15 years earlier under real-world tests; hence, diesel cars emit around 20 times more nitrogen oxides than ...