Deactivation by SO2 of MnOx/Al2O3 catalysts used for the selective catalytic reduction of NO with NH3 at low temperatures

✍ Scribed by W Sjoerd Kijlstra; Monty Biervliet; Eduard K Poels; Alfred Bliek

• Book ID: 114299913
• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 209 KB
• Volume: 16
• Category: Article
• ISSN: 0926-3373
• DOI: 10.1016/s0926-3373(97)00089-1

✦ Synopsis

Low loaded alumina supported manganese oxides exhibit a high activity and selectivity for the selective catalytic reduction (SCR) of NO in the temperature range 383±623 K. The impact of low concentrations of SO 2 on the activity of these catalysts has been investigated. Upon SO 2 addition to the ¯ue gas, the catalysts lose their high initial activity in a few hours due to stoichiometric SO 2 uptake. Analysis of the deactivated samples by mercury porosimetry, FTIR, TPR and TPD shows that the deactivation is not due to the formation of (bulk or surface) Al 2 (SO 4 ) 3 or deposition of ammonium sulphates. Comparison of the results with unsupported Mn 2 O 3 and MnO 2 provides evidence that formation of surface MnSO 4 is the main deactivation route. This process is independent of the oxidation state of the manganese and the presence of oxygen in the gas stream. The formed sulphates decompose at 1020 K and are reduced by H 2 at temperatures above 810 K. This means that regeneration of the catalysts is not very feasible. The results restrict practical application of these catalysts to sulphur free conditions. # 1998 Elsevier Science B.V.