The abatement of pollutants contained in the exhaust gas is achieved by designing catalytic converters able to comply with the increasingly stringent legislations; these converters are integrated into the exhaust system with specific technologies.
Generally speaking for the pollutants abatement, in case of gasoline engines 3-way catalytic converters are used (for the abatement of CO, HC and NOx), while for diesel engine two-way catalytic converters are used (to abate CO and HC) along with Diesel Particulate Filter (DPF).
Systems capable of reducing NOx emissions for diesel engines are currently being studied.