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, conversion reached 96% at the temperature of 430 degrees C. 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 0, 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 Mold 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, 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.