Surface Properties of Calcinated Titanium Dioxide Probed by Solvatochromic Indicators: Relevance to Catalytic Applications

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• 作者：Omar A. El Seoud ; Adham R. Ramadan ; Bruno M. Sato ; Paulo A. R. Pires
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：June 17, 2010
• 年：2010
• 卷：114
• 期：23
• 页码：10436-10443
• 全文大小：208K
• 年卷期：v.114,no.23(June 17, 2010)
• ISSN：1932-7455

文摘

Titanium dioxide was obtained by hydrolysis of the corresponding ethoxide, followed by washing, drying, and calcination at 80, 160, 240, 320, 400, and 700 °C, respectively. The following surface properties of the solids obtained were determined as a function of the calcinations temperature: T_Calcn; area by the BET method; Brønsted acidity by titration with sodium hydroxide; empirical polarity, E_T(30); Lewis acidity, α_Surf; Lewis basicity, β_Surf; and dipolarity/polarizability π_Surf^*, by use of solvatochromic indicators. Except for β_Surf whose value increased slightly, heating the samples resulted in a decrease of all of the above-mentioned surface properties, due to the decrease of surface hydroxyl groups. This conclusion has been corroborated by FTIR. Values of E_T(30), α_Surf, and π_Surf^* are higher than those of water and alcohols; the Brønsted and Lewis acidities of the samples correlate linearly. The advantages of using solvatochromic indicators to probe the surface properties and relevance of the results to the applications of TiO₂ are discussed.