Selective Catalytic Reduction Of NO_x Over Fe-ZSM-5

In this work, Fe-ZSM-5 catalysts with different SiO2/Al2O3 ratios and different ion-exchange degrees were prepared , and its catalytic performance in HC-SCR reaction were investigated. It is found that the catalysts persisted SCR activities even when the reaction temperature higher than 500 ℃ under lean condition. Difference in SiO2/Al2O3 ratios of the supports and ion-exchange degrees resulted in different catalytic activity. When the exchange degree is low, the reaction activity lowered with the increasing SiO2/Al2O3 ratio; when the exchange degree reached certain level, the possible interaction of the active ion in catalyst with low SiO2/Al2O3 ratio may result in activity loss. Investigation on catalytic performance in humidity reaction atmosphere showed that the catalyst have the potential applicability for practical use.Catalyst characters were studied by XRD, TPD, SEM and XPS methods. XRD result shows that ion exchanged dispersed well in ZSM-5 when the exchange degree is low. The TPD result shows that Fe species may be different with different ion exchange degrees;the SEM indicates cluster of exchanged ion could not be found; according to the XPS results combined with datum in other papers , Fe2+ plays a key role in the reactions and a mechanism in the reaction was assumed.