A multifunctional catalyst system

A multifunctional catalyst system for reducing harmful exhaust gas emissions from an exhaust gas stream of a stoichiometrically operated engine, the system comprising:

• a) a coating comprising a sulphur oxide and phosphorus trap (SPT) on a first substrate,
• b) a three-way catalyst (TWC) on a second substrate, and
• c) a selective ammonia oxidation catalyst (SAOC) on a third substrate;
• wherein the first and second substrate are different substrates avoiding any overlap between the SPT and the TWC,
• wherein the SPT is positioned upstream from the TWC while the SAOC is positioned downstream from the TWC and the multifunctional catalyst system is adapted for positioning downstream from the stoichiometrically operated engine, which multifunctional catalyst system is adapted to be in fluid communication with the exhaust gas stream,
• wherein the SPT is present in an amount of 10-50 vol % of total TWC volume,
• wherein the SAOC is present in an amount of 10-50 vol % of total TWC volume.