Role of α-Sites in the selective catalytic reduction of NOx with ammonia over Fe-ZSM-5 catalysts

• Published in: Kinetics and catalysis 2012-11, Vol.53 (6), p.747-752
• Main Authors: Doronkin, D. E., Piryutko, L. V., Starokon’, E. V., Panov, G. I., Stakheev, A. Yu
• Format: Article
• Language: English
• Subjects: 2011; Catalysis; Chemistry; Chemistry and Materials Science; Moscow; Physical Chemistry; Russian Congress on Catalysis-Ruscatalysis (October 3–7
• ISSN: 0023-1584; 1608-3210
• DOI: 10.1134/S0023158412050060

The catalytic properties of Fe-ZSM-5 zeolites with different iron contents have been investigated in the selective catalytic reduction (SCR) of NO x with ammonia. The observed catalytic properties the zeolites are correlated with the concentration of the iron-containing sites that are stabilized in the zeolite and effect N 2 O decomposition (α-sites). The catalysts activated at a high temperature to increase the α-site concentration (by a factor of 5–10) are more active in NO x SCR with ammonia than the unactivated samples. However, the difference between the activities of the activated and unactivated catalysts is well below the difference between the α-site concentrations in these catalysts. The nonlinear relationship between these parameters is evidence that the α-sites in Fe-ZSM-5 is not the only factor determining the activity of Fe-ZSM-5 in NO x SCR with ammonia. The activated catalysts show a low activity in nonselective ammonia oxidation and, accordingly, a high selectivity in the target process at high temperatures.