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 ?
The work builds on 2016 research in which groups led by Datye and Yong Wang--who holds a joint appointment in WSU's School of Chemical Engineering and Bioengineering and the Pacific Northwest National Laboratory--found a novel way to trap and stabilize individual platinum atoms on the surface of cerium oxide, a commonly-used component in emissions control catalytic converters. The so-called single-atom catalyst uses platinum more efficiently while remaining stable at high temperatures.
The exhaust system has been replicated up to and partially beyond the second catalytic converter within space constraints in the test cell.
On the other hand, with the evolution of technology, the automobile industry is shifting towards electric vehicles, which will act as a restraint for the global industrial catalytic converters market.
There are two main processes in the system: the conversion of fuel chemical [E.sub.CH] energy into thermal energy [E.sub.T] and then in mechanical energy [E.sub.M] (level A) and cleaning harmful EG components in the catalytic converter (level C).
Catalytic converters are prized by thieves who rip out the devices because they contain the precious metals platinum and palladium.
Eastern is a manufacturer and suppliers of catalytic converters to the aftermarket.
"Police would also like to hear from anyone who has been offered a cheap catalytic converter for sale to make contact."
Dr Benjamin Kingsbury, research associate at Imperial College London's department of chemical engineering, has advanced the existing manufacturing process of catalytic converters to improve the structure of the ceramic block's microscopic channels (right).
A CHARITY in the Vale of Glamorgan has been hit by thieves who stole the valuable catalytic converter from a minibus used by pensioners.
"Thieves can cut the catalytic converter from the exhaust pipe of a parked car.
"I got out and looked underneath it, and sure enough, the catalytic converter was gone."
HE WAS the man who led the development of the catalytic converter only to be ousted in a boardroom coup.