Catalytic behaviour of metal based ZSM-5 catalysts for NOx reduction with NH3 in dry and humid conditions Original Research Article

Some metals (Cu, Cr and Fe) based on zeolite (H-ZSM-5) catalysts were prepared by wet impregnation method. These were characterized by X-ray diffraction and surface area measurements. The reduction of NO by NH3 in the presence of O2 with and without water vapour was determined over these catalysts. FTIR spectra of adsorbed species and TPD study indicate the formation of copper ammonia complex; chemisorption of NH3 and NOx is found on Cu-ZSM-5, whereas in the cases of Cr-ZSM-5 and Fe-ZSM-5, only NH3 chemisorption is observed. Cu-ZSM-5 showed better catalytic activity with water and was superior to other catalysts, which showed lower activity and moderate selectivity. The results indicated that the presence of O2 helps in adsorbing more NO over Cu-ZSM-5. The mechanistic pathways of this proposed reaction are based on earlier findings and on those of the present investigation.