Practice shows that the majority of motorists have rather vague idea about the work of catalytic converter. It is difficult to find a citizen who has never heard that this device contains a large amount of precious metals. Taking into consideration that catalysts deteriorate with time, many people make a wrong conclusion: allegedly precious metals in the device are spent for neutralization of dangerous gases. In fact, this is not the case.
The full and correct name of the car’s catalytic converter is “catalytic converter”. There is also a variant “catalytic converter”. Each of the expanded names much better reflects the essence and principle of operation of this device. Outwardly, the catalytic converter looks like a car muffler: it has the same rounded metal body, from which two metal pipes stick out. Inside the catalytic converter is covered with a thermal insulating layer, and the rest of the space is filled with small honeycombs. In fact, they have a thin layer of precious metal content. Most often, this is platinum mixed with palladium. Recently, however, the platinum in this “family” is increasingly abandoned in favor of cheaper gold.
There is a persistent myth regarding platinum/gold plating with palladium. Allegedly, this layer is gradually consumed by contact with exhaust gases and participation in a chemical reaction. In fact, this is not entirely true. The alloy of the precious metal itself does not enter into a chemical reaction, but only provokes it, “pushing” other molecules to it, thus acting as a catalyst. Actually, this is the reason why the device is called a catalytic catalytic converter.
How does it work in practice? Car fuel and air enter the engine cylinders. The air contains about 30% oxygen and 70% nitrogen (not counting other finer impurities). The fuel combusts, producing primarily water and carbon dioxide. Other substances are produced during combustion, including nitrogen oxides and carbon monoxide. It is these that pose the greatest danger, as they are poisonous. The gas then leaves the engine through the exhaust system, passing through the catalytic converter.
Moving through the catalytic cone, the platinum-coated gases and vapors from the combustion of the fuel undergo another chemical reaction in which the nitrogen oxides are broken down into oxygen and nitrogen. The oxygen in this reaction combines with the carbon monoxide, thereby converting it into carbon dioxide.