There are mainly three types of auto exhaust catalysts:
1. Two-Way Catalysts: These catalysts primarily oxidize CO and HC to CO₂ and H₂O. They are used in older vehicles and in applications where NOx control is not a major concern.
2. Three-Way Catalysts (TWC): These are the most common in modern vehicles and can simultaneously oxidize CO and HC while reducing NOx to N₂. They require precise control of the air-to-fuel ratio to function efficiently.
3. Diesel Oxidation Catalysts (DOC): Specifically designed for diesel engines, these catalysts oxidize CO, HC, and soluble organic fractions of particulate matter into less harmful substances.
