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Indexed by:期刊论文

Date of Publication:2016-03-01

Journal:MICROPOROUS AND MESOPOROUS MATERIALS

Included Journals:EI、SCIE、Scopus

Volume:222

Page Number:235-240

ISSN No.:1387-1811

Key Words:Interlayer expanded zeolite; IEZ; Metal linker; Microporous metallo-silicate; Rietveld analysis

Abstract:Interlayer expansion using silylating agents to connect layer silicates to 3D framework structures has shown to be a versatile synthesis route to new crystalline, microporous frameworks. We demonstrate here that also Me cations can be introduced on the linker sites applying the same synthesis procedure. An acidic aqueous Fe-chloride solution was used in a hydrothermal reaction to convert the layered hydrous silicate precursor RUB-36 into an interlayer expanded zeolite, containing Fe at the linker sites, Fe-IEZ-RUB-36, Si19.14Fe0.86O38(OH)(4). Structure analysis from powder X-ray data using the Rietveld technique confirmed that the porous framework is stable upon calcination and contains Fe on T-sites at the linker position. SEM-EDX analysis is in agreement with the analysis of the electron density maps showing that almost every other linker T-position is occupied by Fe-ions. The material crystallizes in the monoclinic space group Pm with a = 12.200(9) angstrom, b = 13.981(8) angstrom, c = 7.369(2) angstrom, and beta = 106.9(1)degrees. Applying a similar synthesis procedure, the Sn-analog, Sn-IEZ-RUB-36, Si38.6Sn1.4O76(OH)(8), has been obtained and structurally characterized. Despite its limited crystallinity, Rietveld analysis of the PXRD data set confirmed the materials framework topology and chemical composition (a = 23.856(14) angstrom, b = 14.103(7) angstrom, c = 7.412(7) angstrom, in SG Pnm2(1)). We conclude, that the synthesis procedure is flexible and, meanwhile, has been extended to other metal cations such as Ti, Zn, Eu and Al leading to microporous materials with potentially active metal cations on well defined sites of the silicate framework. (C) 2015 Elsevier Inc. All rights reserved.