Sulfate Ions and Boehmite Crystallization in a Sol Made with Aluminum Tri-sec-butoxide and 2-Propanol

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• 作者：Xim Bokhimi ; Antonio Morales ; Jaime S. Valente
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：January 11, 2007
• 年：2007
• 卷：111
• 期：1
• 页码：103 - 107
• 全文大小：557K
• 年卷期：v.111,no.1(January 11, 2007)
• ISSN：1932-7455

文摘

The properties of colloidal particles in a sol prepared with aluminum tri-sec-butoxide and 2-propanol containingdifferent concentrations of sulfuric acid were studied. The particles were nanocapsules with diameters between10 and 50 nm and shells 3.5 nm thick, made of noncrystalline ordered Al-O polynuclear species. When thenanocapsules interacted with each other, their atoms reordered into the crystalline structure of boehmite. Thisinteraction was diminished when the nanocapsule shells were covered with sulfate ions. The concentration ofsulfate ions allowed control of boehmite crystallization, which was completely hindered when the concentrationwas high enough to cover all the nanocapsules in the sample. The initial crystallization of boehmite wasanalyzed in detail; this showed that the formation of crystalline boehmite bars was a consequence of thecontours formed by the interaction between neighboring nanocapsules. This interaction and its control via thesulfate ions determined the texture of the sample when it was calcined, which is important for the applicationsof this system. The study helps to understand the properties of aluminum oxide prepared by the sol-geltechnique, especially when sulfuric acid is the hydrolysis catalyst.