Alkali poisoning of Fe-Cu-ZSM-5 catalyst for the selective catalytic reduction of NO with NH3

Fe (2 wt%)-Cu (1.5 wt%)-ZSM-5 SCR catalyst contacted 1.5 wt% of Na and 1.8 wt% of K in order to simulate poisoning by species more specifically contained in exhaust gases from exhaust gases of diesel engines and power plants. Poisoning agents do not cause loss of surface area nor pore occlusion. XRD and SEM results showed that alkali metals introduction did not deteriorate the crystallinity and morphology of zeolite crystals. However, a significant loss of surface acidity was observed upon alkali-poisoned catalysts causing a dramatic deactivation of the NH-SCR of NO reaction. Na-doped catalyst showed higher low-temperature SCR activity, while potassium has a stronger deactivation effect on Fe-Cu-ZSM-5 than sodium beyond 400 °C