NH3-SCR performance of fresh and hydrothermally aged Fe-ZSM-5 in standard and fast selective catalytic reduction reactions.
Environ Sci Technol
; 47(7): 3293-8, 2013 Apr 02.
Article
em En
| MEDLINE
| ID: mdl-23477804
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.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Temperatura
/
Água
/
Zeolitas
/
Amônia
/
Ferro
Idioma:
En
Revista:
Environ Sci Technol
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
China