EMM-23: A Stable High-Silica Multidimensional Zeolite with Extra-Large Trilobe-Shaped Channels

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• 作者：Tom Willhammar ; Allen W. Burton ; Yifeng Yun ; Junliang Sun ; Mobae Afeworki ; Karl G. Strohmaier ; Hilda Vroman ; Xiaodong Zou
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：October 1, 2014
• 年：2014
• 卷：136
• 期：39
• 页码：13570-13573
• 全文大小：282K
• ISSN：1520-5126

文摘

Stable, multidimensional, and extra-large pore zeolites are desirable by industry for catalysis and separation of bulky molecules. Here we report EMM-23, the first stable, three-dimensional extra-large pore aluminosilicate zeolite. The structure of EMM-23 was determined from submicron-sized crystals by combining electron crystallography, solid-state nuclear magnetic resonance (NMR), and powder X-ray diffraction. The framework contains highly unusual trilobe-shaped pores that are bound by 21鈥?4 tetrahedral atoms. These extra-large pores are intersected perpendicularly by a two-dimensional 10-ring channel system. Unlike most ideal zeolite frameworks that have tetrahedral sites with four next-nearest tetrahedral neighbors (Q⁴ species), this unusual zeolite possesses a high density of Q² and Q³ silicon species. It is the first zeolite prepared directly with Q² species that are intrinsic to the framework. EMM-23 is stable after calcination at 540 掳C. The formation of this highly interrupted structure is facilitated by the high density of extra framework positive charge introduced by the dicationic structure directing agent.