How do catalytic converters work?

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Catalytic converters change harmful substances in a car’s exhaust gasses, such as carbon monoxide, nitric oxide, nitrogen dioxide and hydrocarbons, into less harmful substances like carbon dioxide and water vapour by means of chemical reactions.

The interior of the ‘cat’ is usually filled with a honeycomb structure onto which a coating is applied that contains a catalyst - the substance that creates a reaction with the exhaust gasses, changing their chemical structure.

Precious metals like palladium, rhodium and platinum are commonly used as the catalyst and these have an intrinsic value that means they’re worth salvaging and recycling when the car is scrapped. Unfortunately, these precious metals also make catalytic converters a target for thieves.

Catalytic converters need to work at high temperatures of up to 400 degrees to maximise their efficiency. To achieve this optimum operating temperature the first units were positioned close to the car’s engine but this caused its own issues and the cat has gradually been mover further down the exhaust system...