3-way catalyst

The 3-way catalytic converter is suitable for gas cleaning in gasoline engines, where carbon monoxide (CO), nitrogen oxides (NOx) and unburned hydrocarbons (HC) are converted to carbon dioxide (CO2), nitrogen (N2) and water (H2O). From this simultaneous conversion of air pollutants is the name 3-way cat has emerged.
The regulated 3-way catalytic converter converts over 90% of the pollutants into harmless elements, thus significantly reducing the pollutant emissions of the internal combustion engine. The 3-way kats work best if you want to clean the exhaust from lambda λ = 1 engines. Lambda λ = 1 denotes the mixing ratio of fuel to air.