Gasoline fuelled vehicles utilise a three-way catalyst that can reduce carbon monoxide (CO), hydrocarbon (HC) and oxides of nitrogen (NOx) emissions by over 99% – if the air-to-fuel ratio (AFR) is accurately controlled. Optimised conversion is achieved with an AFR of 14.7:1.
[CO] + O2 → CO2
[HC] + O2 → CO2 + H2O
[NOx] + H2 → N2 + H2O
Composition: Typically, precious metals (Pd, Pt or Rh) with alumina and rare earth oxide, coated on a flow-through monolith.