Catalytic converter:

It is a cylindrical unit installed into the exhaust system of a vehicle, between the exhaust manifold and the silencer. Due to the presence of catalyst in the converter toxic gases in the exhaust, i.e., CO, HC and NO_x are converted into harmless CO₂, H₂O and N₂. Commonly used catalysts are platinum and rodium. A three way catalytic converter can be used in case of a petrol engine only. In diesel engines, only a two-way converter is used.