The promoting mechanism of Ce on the hydrothermal stability of Fe-Beta catalyst for NH3-SCR reaction

The experiment of Fe-Beta catalysts modified by Ce with incipient wetness impregnation methods was carried out for the selective catalytic reduction of NO x with NH 3 . The characteristics of the catalyst before and after hydrothermal treatment were evaluated by the changes of the active sites, acid sites and pore structure. The results showed that the conversion from [Fe 2+ -OX] + to [HO-Fe 3+ -OX] + during the reaction of hydrothermal aging promoted the gradual dehydroxylation and condensation of [HO-Fe 3+ -OX] + to generate larger Fe x O y particles. However, the introduction of Ce slowed down this trend, and [(HO) 2 -Ce-OX] + and [HO-Fe 3+ -OX] + competed with each other in the process of dehydroxylation condensation would not form longer cluster species. The Ce promoted the adsorption and activation of NO x species and more nitrate species in the form of chelated bidentate nitrate, and then improved the formation of NH 4 NO 3 , which would remarkably enhance the activity of Ce-Fe-Beta catalyst after hydrothermal aging. • Ce addition promoted the adsorption and activation of NO x species. • There is a process of [Fe 2+ -OX] + .→[HO-Fe 3+ -OX] + in some Fe species during hydrothermal aging • The hydrothermal stability of Fe-Beta is improved after doping with Ce. • The introduction of Ce slows down the dehydroxylation condensation of reactive Fe species.