Pure Silica Chabazite Molecular Spring: A Structural Study on Water Intrusion−Extrusion Processes

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• 作者：Mickaë ; l Trzpit ; Sé ; verinne Rigolet ; Jean-Louis Paillaud ; Claire Marichal ; Michel Soulard ; Joë ; l Patarin
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：June 19, 2008
• 年：2008
• 卷：112
• 期：24
• 页码：7257 - 7266
• 全文大小：1914K
• 年卷期：v.112,no.24(June 19, 2008)
• ISSN：1520-5207

文摘

Water intrusion−extrusion isotherms performed at room temperature on hydrophobic pure silica chabazite show that the water−Si−CHA system displays real spring behavior. However, differences in pressure−volume diagrams are observed between the first and the other intrusion−extrusion cycles, indicating that some water molecules interact with the inorganic framework after the first intrusion. ²⁹Si and especially ¹H solid-state NMR showed the creation of new defect sites upon the intrusion−extrusion of water and the existence of two kinds of water molecules trapped in the supercage of Si−CHA: a first layer of water strongly hydrogen bonded with the silanols of the framework and a subsequent layer of liquidlike physisorbed water molecules undergoing interaction with the first layer. This hydrogen bonding scheme is also supported by X-ray powder diffraction.