Catalytic Converter in Your Car
A Catalytic Converter is a simple, but very crucial device in your car. The Catalytic Converter essentially converts toxic pollutants that are present in exhaust gases of your car to less toxic pollutants.
Catalytic converters were first introduced in American production cars in 1975. Due to EPA regulations on toxic emissions reductions, the United States Clean Air Act required a 75% decrease in emissions in all new models of vehicles produced after 1975. This decrease required the mandatory use of catalytic converters in automobiles.
The role of a Catalytic Converter gains all the more importance because all our automobiles today use internal combustion engines which are fuelled by either petrol (gasoline) or diesel. Presence of too much or too less oxygen as well as impurities in the engine or in the fuel that gets burnt inside your car’s engine are most likely to produce harmful air pollutants, including the poisonous carbon monoxide gas. To contain the air pollution within the prescribed emission levels, Government authorities across the world have laid down stringent emission norms. And, the Catalytic Converter does exactly that for you!
Catalytic Converter catalyses a redox reaction (oxidation or reduction) inside a metal housing with a ceramic honeycomb-like interior that is equipped with insulating layers. This honeycomb interior features thin wall channels coated with a wash coat of aluminium oxide. It impressively converts almost 98% of the harmful gases produced by your car’s engine into considerably less harmful fumes. This porous coating while increasing the surface area, allows for more reactions to take place. It contains valuable metals such as platinum, rhodium, and palladium, however only 4-9 grams of these precious metals are used in any one catalytic converter.
This vehicle emissions control device uses pretty simple oxidation and reduction reactions to convert the undesirable fumes. Since oxidation is basically the loss of electrons and that reduction is the gaining of electrons, the metals mentioned above achieve this by transferring electrons, and ultimately converting the toxic fumes into less harmful ones. Here, the last section of the converter, which controls the fuel-injection system, comes into the picture. Helped by an oxygen sensor, this control system monitors the percentage of oxygen is in the exhaust stream. Accordingly, it tells the engine computer to make adjustments to the air-to-fuel ratio, thereby enabling the catalytic converter to keep running at the stoichiometric point with optimum efficiency.
The Catalytic Converters are classified into two types, according to the task they perform; Two-way or Three-way catalytic converter. A two-way (or “oxidation”) catalytic converter performs oxidation of carbon monoxide to carbon dioxide, and also the oxidation of hydrocarbons (unburnt and partially burnt fuel) to carbon dioxide and water, while a three-way catalytic converter (TWC) has the ability to control the emission of nitrogen oxides as well.
The catalyst that works inside the Catalytic Converters can turn poisonous if the converter is exposed to exhaust containing substances that coat the working surfaces. It is very important to note here that vehicles equipped with catalytic converters can be run only on unleaded fuels, as lead is the major contaminant that causes Catalytic Converters to become ineffective. In case your car’s engine has a leakage then it may also cause coolant to enter into the combustion chamber, giving way to admission of harmful catalyst contaminants like Phosphorus, Sulphur and Manganese which can damage the catalytic converter permanently. Vehicles equipped with OBD-II diagnostic systems are designed to alert the driver to a misfire condition by means of flashing the “check engine” light on the dashboard.
Without catalytic converters, your vehicle will release hydrocarbons, carbon monoxide, and nitrogen oxide. These gases are not only the major source of ground level ozone, but they also result in smog and cause damage to flora & fauna too. Although catalytic converters are most commonly applied to exhaust systems in automobiles, they are used in trucks, buses, locomotives, motorcycles and electrical generators too.