How do catalytic converters reduce harmful emissions in cars?

Catalytic converters reduce harmful emissions by converting them into less harmful substances through chemical reactions.

A catalytic converter is a device fitted into the exhaust system of a car. Its primary function is to reduce the level of harmful pollutants that a car emits into the atmosphere. It does this by facilitating chemical reactions that convert these harmful gases into less harmful substances.

The harmful gases that are targeted by the catalytic converter include carbon monoxide (a poisonous gas), nitrogen oxides (which contribute to smog and acid rain) and hydrocarbons (which contribute to smog). The catalytic converter is designed to convert carbon monoxide into carbon dioxide, nitrogen oxides into nitrogen and oxygen, and hydrocarbons into carbon dioxide and water.

The catalytic converter is made up of a core of ceramic honeycomb coated with a mixture of metals including platinum, palladium and rhodium. These metals act as catalysts – substances that speed up chemical reactions without being used up themselves. As the exhaust gases pass over the catalysts, the harmful substances react with each other and with the oxygen in the exhaust gases to form the less harmful substances.

For example, the reaction of carbon monoxide with oxygen to form carbon dioxide is facilitated by the platinum and palladium in the converter. The reaction of nitrogen oxides to form nitrogen and oxygen is facilitated by the rhodium. And the reaction of hydrocarbons with oxygen to form carbon dioxide and water is facilitated by both platinum and palladium.

In this way, the catalytic converter plays a crucial role in reducing the environmental impact of cars. However, it's important to note that while the converter reduces the level of harmful emissions, it does not eliminate them entirely. Furthermore, the production and disposal of catalytic converters themselves have environmental impacts, including the mining of the precious metals used in their manufacture.