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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.
A three-way catalytic converter on a gasoline-powered 1996 Dodge Ram Simulation of flow inside a catalytic converter. A catalytic converter is an exhaust emission control device which converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalyzing a redox reaction.
The ECE 15/05 norms (also known as the Luxemburg accord, strict enough to essentially require catalytic converters) began taking effect gradually: the initial step applied to cars of over 2000 cc in two stages, in October 1988 and October 1989. [2] There followed cars between 1.4 and 2.0 liters, in October 1991 and then October 1993.
Monolithic catalyst supports are extruded structures that are the core of many catalytic converters, [1] most diesel particulate filters, and some catalytic reactors. Most catalytic converters are used for vehicle emissions control. Stationary catalytic converters can reduce air pollution from fossil fuel power stations.
When the catalytic converter is cold, air injected at the upstream point burns with the deliberately rich exhaust so as to bring the catalyst up to operating temperature quickly. Once the catalyst is warm, air is injected to the downstream location — the catalytic converter itself — to assist with catalysis of unburned hydrocarbons .
In catalytic converters used on automobiles, the combustion of leaded gasoline produces elemental lead, lead(II) oxide, lead(II) chloride, and lead(II) bromide. Lead alloys with the metals present in the catalyst, while lead oxides and halides coat the catalyst's surfaces, reducing the converter's ability to reduce NOx emissions.
Cordierite Diesel Particulate Filter on GM 7.8 Isuzu. Unlike a catalytic converter which is a flow-through device, a DPF retains bigger exhaust gas particles by forcing the gas to flow through the filter material before exiting; [2] [29] however, the DPF does not retain small particles.
Fluid catalytic cracking is a commonly used process, and a modern oil refinery will typically include a cat cracker, particularly at refineries in the US, due to the high demand for gasoline. [10] [11] [12] The process was first used around 1942 and employs a powdered catalyst. During WWII, the Allied Forces had plentiful supplies of the ...