Structural Chemical Zoning in the Boundary Phase Zeolite TNU-7 (EON)

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• 作者：Bada Han ; Chae-Ho Shin ; Stewart J. Warrender ; Philip Lightfoot ; Paul A. Wright ; Miguel A. Camblor ; and Suk Bong Hong
• 刊名：Chemistry of Materials
• 出版年：2006
• 出版时间：June 27, 2006
• 年：2006
• 卷：18
• 期：13
• 页码：3023 - 3033
• 全文大小：374K
• 年卷期：v.18,no.13(June 27, 2006)
• ISSN：1520-5002

文摘

The synthetic details of the novel large-pore gallosilicate zeolite TNU-7 (EON) under wholly inorganicconditions, together with those of gallosilicate mazzite (MAZ) and mordenite (MOR) which themselvesconsist of the two structural components of TNU-7, are described. When the Na⁺ ion is used as aninorganic structure-directing agent, crystallization of the pure form of each material was found to behighly sensitive both to the presence of Ga in the synthesis mixture and to its concentration. Rietveldrefinements based on the synchrotron X-ray diffraction data for the as-made Na⁺ form of these threegallosilicate zeolites, as well as for the Cs⁺- and Sr²⁺-exchanged forms of TNU-7, allow us to determinethe favored extraframework cation positions in each material. Comparison of their calculated extraframework cation charge values per tetrahedral site suggests the existence of "structural chemical zoning"within the TNU-7 structure: it appears that this metastable zeolite is composed of maz and mor layerswhich are rich and poor in Ga, respectively.