The influence of Si/Al ratio on the catalytic property and hydrothermal stability of Cu-SSZ-13 catalysts for NH^sub 3^-SCR

Cu-SSZ-13 catalysts with three Si/Al ratios of 6, 15 and 30 were synthesized by a one-pot method. The catalytic property and hydrothermal stability of as-prepared catalysts were studied to understand the influence of Si/Al ratio on the NH3-SCR performance over Cu-SSZ-13 catalysts. Although the three...

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Bibliographic Details
Published inApplied catalysis. A, General Vol. 550; p. 256
Main Authors Fan, Chi, Chen, Zhen, Pang, Lei, Ming, Shujun, Zhang, Xiaofeng, Albert, Kouadio Brou, Liu, Peng, Chen, Hanping, Li, Tao
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier Science SA 25.01.2018
Subjects
Acidity
Aluminum
Ammonia
Catalysis
Catalysts
Chemical synthesis
Copper
Hydrothermal treatment
Kinetics
Reduction
Structural stability
Zeolites
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Summary:Cu-SSZ-13 catalysts with three Si/Al ratios of 6, 15 and 30 were synthesized by a one-pot method. The catalytic property and hydrothermal stability of as-prepared catalysts were studied to understand the influence of Si/Al ratio on the NH3-SCR performance over Cu-SSZ-13 catalysts. Although the three catalysts contain equivalent Cu loading, they perform different catalytic activities for NO reduction. The EPR and H2-TPR results clearly show that the Si/Al ratio not only has influence on the nature of Cu species but also on the Cu species distribution. With increasing the Si/Al ratio, the amount of CuO increases while the number of highly stable Cu+ ions decreases. Such a phenomenon could be attributed to the less Al content in high-Si/Al-ratio catalysts. Besides, the acidity is also found to be affected by the Si/Al ratio. The NH3-TPD results demonstrate that the total number of acid sites decreases with increasing the Si/Al ratio. Lacking sufficient acidity is also responsible for the inferior NO reduction activity of Cu-SSZ-13 with Si/Al = 30. Meanwhile, kinetic analysis over fresh catalysts was conducted and the conclusion correlated well with the NH3-SCR performance. Additionally, three catalysts exhibit distinct resistances to hydrothermal treatment. The XRD, N2 physisorption and NH3-SCR performance results consistently indicate the Cu-SSZ-13 with Si/Al = 15 is much more resistant to hydrothermal aging than another two catalysts probably due to its considerably stability of zeolite structure and Cu ions.
ISSN:0926-860X
1873-3875