Simultaneous Catalytic Removal of Nitrogen Oxides and Soot from Diesel Exhaust Gas over Potassium Modified Iron Oxide

Iron oxide modified by potassium, i.e. Fe 1.9 K 0.1 O 3 , exhibits high catalytic performance for the simultaneous conversion of soot and NO x into CO 2 and N 2 . The present study shows that long‐time treatment of the catalyst leads to a drastic decrease in the activity, whereas even the aged catalyst maintains considerable activity. On the other hand, long‐time treatment causes selective N 2 formation, i.e. no more formation of the byproduct N 2 O. This alteration of catalytic performance is likely due to agglomeration of the promoter potassium being present at the surface of catalyst. Detailed experiments were carried out with a more realistic diesel model exhaust gas to confirm that Fe 1.9 K 0.1 O 3 is a suitable catalyst for the simultaneous removal of soot and NO x between 350 and 480 °C. It was assumed that (CO) intermediates, formed by the catalytic reaction of NO x and oxygen with the soot surface, are the reactive species in NO x ‐soot conversion.