When the high-temperature automotive exhaust go through the purification device, the purifying agent in the catalytic converter will enhance the activity of the three harmful gases
CO, HC and NOx, which make them acting oxidation - reduction reaction. CO
oxidizes to a colorless, non-toxic gas
CO2; HC compounds oxidize to H
2O and CO
2; NOx reduce to N
2 and O
2. The three harmful gases convert into harmless gases, which make the automobile exhaust purified.