Catalysis involves the use of substances known as catalysts to speed up chemical reactions without being consumed in the process. In exhaust gas treatment, catalytic converters are employed. These converters contain a ceramic or metallic substrate coated with catalysts such as platinum, palladium, and rhodium. The catalytic reactions typically occur in three stages:
1. Oxidation of Carbon Monoxide (CO): CO is oxidized to carbon dioxide (CO₂). 2. Oxidation of Hydrocarbons (HC): Unburnt hydrocarbons are converted to CO₂ and water (H₂O). 3. Reduction of Nitrogen Oxides (NOx): NOx is reduced to nitrogen (N₂) and oxygen (O₂).
