Exhaust gas aftertreatment system in an exhaust gas system of an ammonia combustion engine, method and use thereof

An exhaust gas aftertreatment system in an exhaust gas system of an ammonia combustion engine, the exhaust gas system can be traversed by an exhaust gas flow of the ammonia internal combustion engine, comprising:

• a passive SCR catalyst,
• an oxidation catalyst with which ammonia contained in the exhaust gas flow can be oxidized, and
• a regulated SCR catalyst,
• wherein the oxidation catalyst is arranged in the exhaust gas system downstream of the passive SCR catalyst, and the regulated SCR catalyst is arranged in the exhaust gas system downstream of the oxidation catalyst,
• wherein the exhaust gas aftertreatment system further comprises at least one N2O decomposition catalyst that is arranged in the exhaust gas system upstream of the passive SCR catalyst or downstream of at least one of the passive SCR catalyst, the oxidation catalyst, or the regulated SCR catalyst, and
• wherein, prior to the treatment with the exhaust gas aftertreatment system, the exhaust gas flow comprises water in a proportion of 5 to 25 percent by volume.