Reduction of Nitrogen Oxides by Ammonia Over Iron‐Containing Catalysts

Selective catalytic reduction (SCR) of NO x by NH 3 is an efficient technology for the removal of nitrogen oxides from diesel exhaust. It is a disadvantage that the active component in commercial catalysts, V 2 O 5 , is toxic and melts at ∼650 °C. An alternative catalyst system, based on iron as the active component, was developed in this work. For this purpose, a number of supports were taken and impregnated with Fe 2 O 3 and Fe 2 O 3 /WO 3 by an incipient wetness technique. The synthesized catalysts were tested in a diesel model exhaust using temperature programmed reaction. The screening accomplished to date, resulted in a 5.8 mol.‐% Fe 2 O 3 /Al 2 O 3 catalyst that exhibited outstanding activity in the temperature range between 150–375 °C with selective formation of N 2 . However, this catalyst was significantly deactivated by thermal aging at 600 °C. In contrast, the activity of the sample with 1.4 mol.‐% Fe 2 O 3 and 0.8 mol.‐% WO x showed very high thermal stability as well as selective N 2 production over the whole temperature regime, but it had lower SCR activity.