Selective Catalytic Reduction of N2O by CO over Fe-Beta Zeolites Catalysts: Influence of Iron Species Distribution

Abstract

In this paper, selective catalytic reduction (SCR) of N2O by CO was investigated over Fe-beta zeolites catalysts. The catalysts were prepared by wet ion-exchange (IE), impregnation (IM) and solid state ion-exchange (SSIE) methods. These catalysts were characterized by XRD, UV–vis DR spectroscopy, H2-TPR, TPD and in-situ DRIFTS. At 350 °C, more than 90% N2O conversion could be obtained over the Fe-beta-IE catalyst. The activity for N2O removal of Fe-beta-IE was higher than Fe-beta-IM and Fe-beta-SSIE catalysts. The UV–vis spectra showed that 84.2% of isolated Fe(III) ion appeared on Fe-beta-IE catalyst. It indicated that the isolated Fe(III) ions might be considered as the active sites for N2O reduction. Besides, in the presence of H2O, the activities in CO-SCR for N2O removal over Fe-beta catalysts were inhibited, which might be due to the hydroxylation deactivation of iron species and excess accumulation of carbonates.