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学科主题: 物理化学
题名: A 57Fe MOSSBAUER SPECTROSCOPIC STUDY OF LaFexAl(12-x)O19 HEXAALUMINATE CATALYSIS FOR HIGH CONCENTRATION N2O DECOMPOSITION
作者: Tian M(田鸣) ;  Wang XD(王晓东) ;  Zhu YY(朱燕燕) ;  Wang JH(王军虎) ;  Zhang T(张涛)
会议名称: International Conference on the Applications of the Mossbauer Effect
会议日期: 2009-7-19
出版日期: 2009-07-19
会议地点: Austria
通讯作者: Tao Zhang
部门归属: 十五室
主办者: Vienna University of Technology
摘要: In recent years, hexaaluminates are of interest as methane combustion catalysts due to the high thermal stability. In our previous work, we reported that Ir and Fe- substituted Ba-hexaaminates were highly active and stable catalysts for N2O decompositon [1]. In the present work, we studied the structure of LaFexAl(12-x)O19 focusing on the Fe sites and the role played in the N2O decomposition. Fig.1 showed the catalytic performances of N2O decomposition on LaFexAl(12-x)O19 as a function of reaction temperature. The activity was enhanced greatly by the incorporation of iron, suggesting that iron was the active component. The N2O conversion increased with the Fe content from x=0 to x=1 and further addition of Fe decreased the catalytic activity. Fig. 2 showed 57Fe Mössbauer spectra of LaFexAl(12-x)O19 at room temperature. It could be found that the spectrum was fitted by two doublets with differnt values of quadrupole splitting (QS) and isomer shift (IS), which could be assigned to tetrahedral (T) and trigonal bipyramidal (Tr) sites, respectively. Table.1 showed 57Fe Mössbauer parameters of LaFexAl(12-x)O19 catalysts at room temperature. Iron ions were exclusively in the 3+ oxidation state, which was deduced from the IS values. Moreover, Fe3+ always occupied the T and Tr position in the ratio of 4 :1 independent on the Fe content with respect to the relative resonance area of Fe3+. Tr position had larger QS value, which readily donated electron to the antibonding orbitals of N2O, thus facilitating the activation of N2O. So, we speculated that Fe3+ in Tr position contributed more to N2O decomposition than Fe3+ in T position. On the other hand, QS value of Tr site significantly increased with the increase in Fe content from x=0.5 to x=1, which might be responsible for the increase of activity. However, futher addition of Fe resulting in the decrease of activity might be attributed to the decrease in QS values of T position which did not favor N2O activation. Fe3+ locating in the Tr sites in the La-hexaaluminates lattice contributed a lot to N2O decomposition.
语种: 中文
内容类型: 会议论文
URI标识: http://cas-ir.dicp.ac.cn/handle/321008/113518
Appears in Collections:中国科学院大连化学物理研究所_会议论文

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Recommended Citation:
Tian M,Wang XD,Zhu YY,et al. A 57Fe MOSSBAUER SPECTROSCOPIC STUDY OF LaFexAl(12-x)O19 HEXAALUMINATE CATALYSIS FOR HIGH CONCENTRATION N2O DECOMPOSITION[C]. 见:International Conference on the Applications of the Mossbauer Effect. Austria. 2009-7-19.
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