Three-way catalysts are used in gasoline engines to control emissions of nitrogen oxides, carbon monoxide, and hydrocarbons simultaneously. The name "three-way" refers to the three pollutants it targets. These catalysts work by promoting chemical reactions that convert these pollutants into less harmful gases:
2NO + 2CO → N2 + 2CO2 2NO + 2H2 → N2 + 2H2O
The efficiency of three-way catalysts depends on maintaining a precise air-fuel ratio, which is typically around the stoichiometric point.
