Selective Catalytic Reduction of NO with Ammonia over Fe Promoted Mo/ZSM-5 Catalysts

The Fe-Mo/ZSM-5 catalysts with different Fe/Mo molar ratios were prepared by using impregnation method.The activity of Fe-Mo/ZSM-5 catalysts for selective catalytic reduction of NO with ammonia and the effects of reaction conditions were also studied.It was found that Fe-Mo/ZSM-5 is more active than both of Mo/ZSM-5 and Fe/ZSM-5 separately,and it exhibits the best performance for SCR reaction when n(Fe)/n(Mo)ratio is 1.5,for which the highest NO_ x conversion reached 96% at the temperature of 430 ℃.The experiment results also show that Fe-Mo/ZSM-5 catalyst has a good stability of SCR reaction,for higher catalytic activity was gained under the condition of high space velocity and varied O_ 2 concentrations.The bulk phase and surface structures were determined by XRD,XPS techniques respectively.The results show that there is a strong interaction among Fe,Mo and HZSM-5,and the surface Mo_ 3d percentage is the largest when n(Fe)/n(Mo)ratio is 1.5,which may be related to its better catalytic performance for catalytic reduction of NO.It is also important to notice that NO_ 2 was not detected during the XPS measurement,and NO was the main species during SCR reaction on the surface of Fe-Mo/ZSM-5 catalyst.From this it can be deduced that NO is directly reacted with ammonia to form nitrogen and water on the surface of the catalyst.