What is a catalytic converter

All modern car exhaust systems include a catalytic converter. This device is designed to reduce the level of emission of harmful substances with the exhaust gases into the atmosphere. The catalytic converter is used both on diesel power units and on gasoline ones. Install it either directly behind the exhaust manifold, or directly in front of the silencer. The exhaust gas neutralizer consists of a carrier unit, a thermal insulation, a housing.

Device

The main element is the carrier. It is made of refractory ceramics. The design of such a unit consists of a large number of longitudinal cells, significantly increasing the area of contact with the exhaust gases. Their surface is covered with special catalysts (palladium, platinum and rhodium). Thanks to these elements, there is an acceleration of chemical reactions.

Palladium and platinum are oxidative catalysts. They provide oxidation of hydrocarbons and, accordingly, promote their conversion into carbon monoxide, carbon dioxide and water vapor. A rhodium is a reducing catalyst. It is used to restore nitrogen oxides to harmless nitrogen. It turns out that three types of catalysts reduce the content of three different harmful substances in the exhaust gases. Therefore, this device is called a three-way catalytic converter.

The carrier unit is housed in a metal casing. Between them is a heat-insulating layer. In the body of the catalyst is an oxygen sensor.

Effective operation of the device under consideration is achieved at a temperature of 300 ° C, in which case about 90 percent of harmful substances are delayed (for this purpose the catalytic converter is installed immediately behind the exhaust manifold).

Features

Catalysts quite effectively reduce the toxicity of exhaust gases and at the same time have practically no effect on engine power and fuel consumption. If this device is present, the reverse pressure will increase slightly, as a result of which the power unit of the car loses 2-3 liters. from. Theoretically, the exhaust gas catalyst can serve forever, because precious metals are not consumed during chemical reactions. However, as practice shows, the service life of these devices has its limit.

For example, one of the reasons for the failure of the neutralizers is a fragile cell ceramics, which, due to a sudden shaking (if the car hits the pothole at a speed, falls into a pothole, or even strikes the catalyst body for anything), it can collapse, which leads to failure Mentioned device. Now began to appear converters, which instead of ceramics - a metal monolith. They are more resistant to destruction. Another reason for the breakdown of the catalytic converter is fuel. Leaded gasoline is rich in tetraethyl lead, which "greases" the surface of the cells. As a result, all reactions stop. The next enemy of the catalyst is the wrong composition of the fuel. So, a mixture containing an increased amount of hydrocarbons, just ruins the device, and too poor causes a sharp overheating, which can lead to the destruction of the monolith. No less dangerous and sudden temperature changes, for example, when the car enters a puddle. This can also damage the ceramic.

In general, the catalytic converter, like any other mechanism, is affected by operating conditions.