Compact exhaust gas aftertreatment system

An apparatus for installation in an exhaust gas train of an internal combustion engine, the exhaust gas train comprising a main exhaust and a branch exhaust that branches off from and rejoins the main exhaust, the apparatus comprising:

• at least one compensator for compensating relative movements between part of the exhaust gas train and at least one of the internal combustion engine and another part of the exhaust gas train;
• a reservoir containing a reductant which splits off ammonia when heated;
• a metering device for adding said reductant to a partial exhaust gas flow at a feed point in the branch exhaust;
• an SCR catalyzer in the main exhaust downstream of where the branch exhaust rejoins the main exhaust, wherein the SCR catalyzer reduces nitrogen oxides in the exhaust gas to nitrogen and water vapor by means of the split-off ammonia;
• and
• an oxidation catalyzer in the branch exhaust upstream of the feed point, wherein the oxidation catalyzer oxidizes at least one of ammonia and reductant decomposition products in the exhaust gas under engine operating conditions in which the exhaust gas flows toward the internal combustion engine;
• wherein the oxidation catalyzer is arranged inside at least one of the compensator and a part of the exhaust gas train permanently connected to the compensator, and
• wherein the at least one of the compensator and the part of the exhaust gas train permanently connected to the compensator has an inside diameter that is larger than the outside diameter of the oxidation catalyzer arranged therein.