capable of decomposing to liberate ammonia under operating conditions then the exhaust gas was passed through a first scr catalyst 3 having a volume of 26 l this catalyst contained vanadium oxide tungsten oxide titanium oxide as a catalytically active component and at a space velocity of about 90 000 1 h at the rated power output exhibited a no x conversion of less than 50 of the nitrogen oxides present in the raw emission upon passage through this first scr catalyst the exhaust gas was passed through a catalytically activated particulate filter 4 containing a wall flow filter substrate where an oxidation catalytically active coating containing 2 g of platinum as a catalytically active component was incorporated in the walls between the inlet and outlet channels see e g fig4 upon passage through the particulate filter uws was fed 2 b into the exhaust gas again and the exhaust gas was passed through a second scr catalyst the second scr catalyst 5 had a total volume of 35 l and contained an iron exchanged zeolite compound as a catalytically active component a highly selective ammonia oxidizing catalyst asc 6 was contained in the total volume of the second scr catalyst as a coating zone deposited on the outflow side the.