Alkali Resistant Fe-Zeolite Catalysts for SCR of NO with NH3 in Flue Gases

Fe-zeolite catalysts were prepared by ion-exchange and characterized by nitrogen physisorption, electron paramagnetic resonance (EPR) spectroscopy, NH3-temperature programmed desorption (TPD), H-2-temperature programmed reduction (TPR) and Energy dispersive X-ray spectroscopy (EDX) methods. The effect of potassium doping on the acidic and redox properties of the Fe-zeolite catalysts were studied. The prepared catalysts showed high surface area and surface acidity. This is essential for increased alkali resistivity in comparison with conventional metal oxide supports like, e. g. TiO2 and ZrO2, towards e. g. potassium salts in flue gases from biomass fired power plants. These properties allowed both undoped and potassium doped Fe-zeolite catalysts to posses high activity during the selective catalytic reduction (SCR) of NO with NH3. The extent of deactivation of the Fe-zeolite catalysts was further compared with commercial V2O5-WO3-TiO2 catalyst (VWT) with various levels of potassium poisoning. While VWT catalysts severely deactivated at relative low potassium concentration levels the Fe-zeolite catalysts also showed superior alkali resistivity even at high potassium loadings.