DOCs function by providing a surface coated with precious metal catalysts, typically platinum (Pt), palladium (Pd), and sometimes rhodium (Rh). When exhaust gases pass over these catalysts, a series of oxidation reactions occur. For example, carbon monoxide is oxidized to carbon dioxide, and hydrocarbons are converted to carbon dioxide and water. These reactions are facilitated by the high surface area of the catalyst and the optimal temperature conditions within the exhaust system.
