Influence of the Preparation Method and Used Support on the Activity of Fe-Loaded Zeolites Catalysts for the NH3-SCR of NOx
Résumé
A series of Fe-loaded zeolites catalysts were prepared by impregnation and in-situ hydrothermal synthesis, and the influence of the preparation method and the support used (ZSM-5, Beta and LTL) on the SCR-NH3 activity was studied. These catalysts after aged were characterized by N2 adsorption, ICP, RMN, XRD, XPS and TEM analysis. Iron species on the surface were assigned to the Fe3+ ions and the small amount of Fe2+ in the case of the hydrothermal catalysts, whereas the impregnated catalysts presented the formation of Fe3O4 oxides, which resulted in difference in SCR activity. The hydrothermal catalysts presented higher activity, N2 selectivity and lower N2O formation than the impregnated one. This could be a consequence of the partial pores blockage of the zeolite and the Fe3O4 oxides formation, when the impregnated method was used. Moreover, the framework structure and/or pore geometry of the used support was crucial for determining the SCR activity.