catalytic converter

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catalytic converter:

see internal-combustion engineinternal-combustion engine,
one in which combustion of the fuel takes place in a confined space, producing expanding gases that are used directly to provide mechanical power.
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catalytic converter

[¦kad·əl¦id·ik kən′vərd·ər]
(chemical engineering)
A device that is fitted to the exhaust system of an automotive vehicle and contains a catalyst capable of converting potentially polluting exhaust gases into harmless or less harmful products.

Catalytic converter

An aftertreatment device used for pollutant removal from automotive exhaust. Since the 1975 model year, increasingly stringent government regulations for the allowable emission levels of carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen (NOx) have resulted in the use of catalytic converters on most passenger vehicles sold in the United States. The task of the catalytic converter is to promote chemical reactions for the conversion of these pollutants to carbon dioxide, water, and nitrogen.

For automotive exhaust applications, the pollutant removal reactions are the oxidation of carbon monoxide and hydrocarbons and the reduction of nitrogen oxides. Metals are the catalytic agents most often employed for this task. Small quantities of these metals, when present in a highly dispersed form (often as individual atoms), provide sites upon which the reactant molecules may interact and the reaction proceed.

Two types of catalyst systems, oxidation and three-way, are found in automotive applications. Oxidation catalysts remove only CO and HC, leaving NOx unchanged. Platinum and palladium are generally used as the active metals in oxidation catalysts. Three-way catalysts are capable of removing all three pollutants simultaneously, provided that the catalyst is maintained in a “chemically correct” environment that is neither overly oxidizing nor reducing. In both oxidation and three-way catalyst systems, the production of undesirable reaction products, such as sulfates and ammonia, must be avoided.

Maintaining effective catalytic function over long periods of vehicle operation is often a major problem. Catalytic activity will deteriorate due to two causes, poisoning of the active sites by contaminants, such as lead and phosphorus, and exposure to excessively high temperatures. To achieve efficient emission control, it is thus paramount that catalyst-equipped vehicles be operated only with lead-free fuel and that proper engine maintenance procedures be followed. See Automotive engine

catalytic converter

a device using three-way catalysts to reduce the obnoxious and poisonous components of the products of combustion (mainly oxides of nitrogen, carbon monoxide, and unburnt hydrocarbons) from the exhausts of motor vehicles
References in periodicals archive ?
com/research/hxcmsx/global_automotive) has announced the addition of the "Global Automotive Catalytic Converter Market 2015-2019" report to their offering.
As a further measure, have your catalytic converter etched or forensically marked and place stickers in the windscreen to say it has been done.
The minibus, used by Dinas Powys Voluntary Concern, is out of action after thieves stole the catalytic converter while it was locked in a council compound.
APPEAL: Det Insp Jim Griffiths is investigating the theft of catalytic converters, shown above
Police regularly carry out checks on scrap metal dealers, which is where the stolen catalytic converters end up.
2, catalytic converters were stolen from a pair of vehicles while they were parked outside a medical clinic near downtown Springfield.
The catalytic converters will be used by the company's production plants in China.
Anyone with any information about the catalytic converter thefts should contact police on 08451 25 35 45.
Catalytic converters, which contain precious metals, are each worth around pounds 60 to thieves.
Meanwhile in Santa Clarita, two men and two women were arrested Friday on suspicion of stealing catalytic converters in the area, which has seen about 15 catalytic-converter thefts since March 1, authorities said.
Thieves got away from the Mill Street lot with two catalytic converters from a Nissan Quest minivan and a Suzuki sport utility vehicle.
Catalytic converters use platinum to keep exhaust pollutants from vehicles down to an acceptable level, however over the years this precious metal content is slowly lost through exhaust pipes.