The influence of poisoning on the deactivation of DeNOx catalysts

This paper summarizes the results of a research on the influence of the poisoning of the SCR catalyst on its structure. Samples of commercially available SCR catalysts were exposed to real flue gases inside a pulverized coal boiler co-firing coal and biomass. The catalysts were investigated by SEM-EDS, XRD, AAS, UV-vis and 1-butene isomerization as a test reaction. Additionally, ash collected from the catalysts was characterized. The obtained results showed a decrease in the activity by ash and alkali metals originating from biomass. Neither the structural changes in the support nor the changes in the oxidation state and distribution of vanadium were observed during the entire testing period. The acidity of the catalyst, operated for the shortest period (2270 h), increased due to the formation of sulfate species arising from the presence of SO2 in the flue gases. The role of sulfate species and alkali cations in poisoning of catalytic sites is discussed. (C) 2015 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.