Probing the reactivity of adsorbed NO species by the CO and H2 pulse during NO decomposition on Cu-ZSM-5

被引:12
作者
Konduru, MV [1 ]
Chuang, SSC [1 ]
Kang, XH [1 ]
机构
[1] Univ Akron, Dept Chem Engn, Akron, OH 44325 USA
来源
JOURNAL OF PHYSICAL CHEMISTRY B | 2001年 / 105卷 / 44期
关键词
D O I
10.1021/jp0125496
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The reactivity of adsorbed NO and the nature of Cu sites on under-, over-exchanged, and silane-treated Cu-ZSM-5 have been probed by the CO and H-2 pulse during NO decomposition at 673 K. Cu+(NO) was identified to be the active adsorbate responsible for NO decomposition to N2O and O-2 as well as to N-2 and O-2. Pulsing CO and H-2 into the NO flow facilitates the reduction of Cu2+ to Cu+ and increases Cu+(NO) concentration, resulting in an enhancement of N2O formation rate on under-exchanged Cu-ZSM-5-83/silane-treated Cu-ZSM-5-523 and an acceleration of N-2 and O-2 formation rates on over-exchanged Cu-ZSM-5-127 and -523. The difference in the product formation among these catalysts is attributed to the isolation of Cu sites on the silane-treated Cu-ZSM-5-527 and under-exchanged Cu-ZSM-5-83 catalyst as well as the presence of Cu-dimer sites (Cu-O-Cu) on the over-exchange Cu-ZSM-5 catalyst. In contrast to the widely postulated steps for N-2 formation via N2O, the profiles of N-2, N2O, O-2, and IR observable adsorbates during the CO and H-2 Pulse suggest that N-2 can be formed without involvement of N2O during NO decomposition.
引用
收藏
页码:10918 / 10926
页数:9
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