Molybdenum loaded on HZSM-50: A catalyst for selective catalytic reduction of nitrogen oxides

A series of Mo/ZSM-5 samples were prepared by an impregnation method. The catalytic Studies show that the catalytic activity of Mo/ZSM-5 for SCR of NOx, is strongly influenced by the Mo content loaded on HZSM-5 zeolites. The temperatures at which maximum NOx, conversion was obtained declined with increasing Mo content. Furthermore, the Si/Al ratio also has a distinct effect on catalytic performance over the Mo/ZSM-5 catalyst; the sample with the lowest Si/Al ratio of 28 is much better than silicon-richer samples at higher temperatures. XPS and NO-TPD results indicate that the catalytic activity of Mo/ZSM-5 samples may be related to the percentage of Mo oil the surface of ZSM-5, since the surface Mo species can considerably change the capacity of NO adsorption oil the surface of Mo/ZSM-5, which may promote the formation or some kind of active sites for catalytic reduction of NOx.