Influence of Mn and Fe Addition on the NOx Storage–Reduction Properties and SO2 Poisoning of a Pt/Ba/Al2O3 Model Catalyst

This work deals with the effect of Mn or Fe addition on the NOx storage–reduction properties of a Pt/Ba/Al2O3 model catalyst. NOx storage capacity, SO2 poisoning and regeneration and NOx removal efficiency under rich/lean cycling conditions are studied. Fe addition to Pt/Ba/Al2O3 leads only to a small increase of NOx storage capacity, and more interestingly, to a better sulfur removal due to the inhibition of bulk barium sulfate formation. Unfortunately, the NOx storage property cannot be fully recovered. Moreover, Fe addition results in a decrease in the NOx removal efficiency. Mn addition also improves the NOx storage capacity, but no significant influence on the sulfur elimination is observed. Mn-doped catalyst does not improve the NOx removal efficiency, but NH3 selectivity is found to drastically decrease at 400 °C, from 20 to 3%. In addition, the NOx conversion can be improved at higher H2 concentration in the rich pulse, always keeping NH3 selectivity at low level.