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

摘要

Iron oxide modified by potassium, i.e. Fe_1.9K_0.1O_3, exhibits high catalytic performance of 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_2O. This altreation of catalytic performance is likely due to agglomeration of the promote potassium being present at the surface of catalyst. Detailed experiments were carried out with a more realistic diesel mdoel exhaust gas to confirm that Fe_1.9K_0.1O_3 is a suitable catalyst for the simultaneous removal of soot and NO_x between 350 and 480 deg C. It was assumed that (CO) intermediaets, formed by the catalytic reaction of NO_x and oxygen with the soot surface, are the reactive species in NO_x-soot conversion.