title: NH3-SCR performance of fresh and hydrothermally aged Fe-ZSM-5 in standard and fast selective catalytic reduction reactions.
abstract: Hydrothermal stability is one of the challenges for the practical application of Fe-ZSM-5 catalysts in the selective catalytic reduction (SCR) of NO with NH3 (NH(3)-SCR) for diesel engines. The presence of NO(3) in the exhaust gases can enhance the deNOx activity because of the fast SCR reaction. In this work, a Fe-ZSM-5 catalyst was prepared by a solid-state ion-exchange method and was hydrothermally deactivated at 800 °C in the presence of 10% H(2)O. The activity of fresh and hydrothermal aged Fe-ZSM-5 catalysts was investigated in standard SCR (NO(2)/NOx = 0) and in fast SCR with NO(2)/NOx = 0.3 and 0.5. In standard SCR, hydrothermal aging of Fe-ZSM-5 resulted in a significant decrease of low-temperature activity and a slight increase in high-temperature activity. In fast SCR, NOx conversion over aged Fe-ZSM-5 was significantly increased but was still lower than that over fresh catalyst. Additionally, production of N(2)O in fast SCR was much more apparent over aged Fe-ZSM-5 than over fresh catalyst. We propose that, in fast SCR, the rate of key reactions related to NO is slower over aged Fe-ZSM-5 than over fresh catalyst, thus increasing the probabilities of side reactions involving the formation of N(2)O.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Shi
authors.forename: Fudong
authors.initials: F
authors.lastname: Liu
authors.forename: Lijuan
authors.initials: L
authors.lastname: Xie
authors.forename: Wenpo
authors.initials: W
authors.lastname: Shan
authors.forename: Hong
authors.initials: H
authors.lastname: He
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D002384:Catalysis; D007501:Iron / Q000737:chemistry*; D009569:Nitric Oxide; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction; D017641:Zeolites / Q000737:chemistry*
chemical_list: C570564:ZSM-5 zeolite; D014867:Water; D017641:Zeolites; D009569:Nitric Oxide; D000641:Ammonia; D007501:Iron