Distribution of Aluminum in the Periodical Building Units of Faujasites

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• 作者：Tam&aacute ; s I. Kor&aacute ; nyi ; J&aacute ; nos B.Nagy
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：February 15, 2007
• 年：2007
• 卷：111
• 期：6
• 页码：2520 - 2524
• 全文大小：78K
• 年卷期：v.111,no.6(February 15, 2007)
• ISSN：1932-7455

文摘

Four NH₄-Y faujasites (FAU) with different Si/Al ratios were characterized by ²⁷Al and ²⁹Si magic-anglespinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The quantitative contributions of the Alsites, defect-free Si(nAl), and silanol groups to the different double-six-ring (D6R) periodical building units(PerBUs) of the zeolite framework were calculated from the various Si/Al ratios and relative ²⁷Al and ²⁹SiNMR signal intensities. Four different PerBU systems were assumed in the FAU structure, but only thedistribution of PerBUs containing three, two, or one Al atom pairs in body-diagonal positions of D6Rs followedthe composition of the framework with appropriate precision in the studied composition range (Si/Al = 2.6-19.5). Contrary to BEA, FER, and MOR zeolites, the PerBUs of FAU do not contain Al atoms in unpaired"lone" positions.