10.18453/rosdok_id00001491 Pérez Vélez, Roxana Roxana Pérez Vélez http://d-nb.info/gnd/1065921160 Universität Rostock 2015 540 Chemistry & allied sciences 2015 en http://purl.uni-rostock.de/rosdok/id00001491 urn:nbn:de:gbv:28-diss2015-0041-9 The selective catalytic reduction of NOx by ammonia (NH3-SCR) has widely applied in the abatement of NOx. Fe-ZSM-5 is a potential catalyst, showing high performance in standard SCR (mainly NO) at > 400°C and in fast SCR (NO/NO2 = 1) at ≥ 250°C. The identification of the active species in Fe-ZSM-5 catalysts and reaction mechanism for SCR reactions were investigated by in situ and operando EPR, UV-Vis and FTIR spectroscopy. The spectroscopic studies demonstrate the role of NO2 to reoxidize isolated Fe(II) to the active Fe(III) at β and γ sites, and attribute them the higher activity in fast SCR.