Combined Experimental and Computational Approaches To Elucidate the Structures of Silver Clusters inside the ZSM-5 Cavity
Combined Experimental and Computational Approaches To Elucidate the Structures of Silver Clusters inside the ZSM-5 Cavity
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DOI：
10.1021/jp508150w
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发表时间：
2014-10
影响因子：
3.7
通讯作者：
T. Yumura;Akira Oda;Hiroe Torigoe;Atsushi Itadani;Y. Kuroda;T. Wakasugi;Hisayoshi Kobayashi
中科院分区：
文献类型：
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作者：
T. Yumura;Akira Oda;Hiroe Torigoe;Atsushi Itadani;Y. Kuroda;T. Wakasugi;Hisayoshi Kobayashi
实验和计算分析的结合表明，在Ag-ZSM-5沸石中纳米尺寸的空腔内存在Ag 3或Ag 4簇，其使用常规的离子交换方法由H-ZSM-5在硝酸银水溶液中形成。在实验分析过程中，我们通过紫外-可见漫反射和X射线吸收精细结构（XAFS）测量研究了Ag-ZSM-5的结构和吸收性质。扩展XAFS（EXAFS）分析结果表明，ZSM-5分子筛空穴中的团簇具有约2.6埃的Ag-Ag分离。UV-vis测量表明，在473 K下处理的样品中，位于腔中的团簇呈现出三个中心约为255、287和331 nm的显著吸收带。在573或673 K处理的Ag-ZSM-5在约303和319 nm处出现新的紫外可见吸收带。对Ag-ZSM-5分子筛的结构和吸附性能的实验结果可以很好地重现。
A combination of experimental and computational analyses suggested the presence of Ag3 or Ag4 clusters inside a nanometer-sized cavity in Ag–ZSM-5 zeolites, which were formed from H–ZSM-5 using the conventional ion-exchange method in an aqueous silver nitrate solution. During the experimental analyses, we investigated the structural and absorption properties of Ag–ZSM-5 through UV–vis diffuse reflectance and X-ray absorption fine structure (XAFS) measurements. The results from the extended XAFS (EXAFS) analysis indicated that clusters contained in the ZSM-5 cavity have Ag–Ag separations of approximately 2.6 A. The UV–vis measurements indicated that the clusters located in the cavity present three prominent absorption bands centered at approximately 255, 287, and 331 nm for the sample treated at 473 K. The Ag–ZSM-5 treated at 573 or 673 K presents new UV–vis bands at approximately 303 and 319 nm. The experimental results regarding the structural and absorption properties of Ag–ZSM-5 could be well-reproduce...