Controlled Interactions between Anhydrous Keggin-Type Heteropolyacids and Silica Support: Preparation and Characterization of Well-Defined Silica-Supported Polyoxometalate Species
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- 作者：Eva Grinenval ; Xavier Rozanska ; Anne Baudouin ; Elise Berrier ; Franoise Delbecq ; Philippe Sautet ; Jean-Marie Basset ; Frdric Lefebvre
- 刊名：Journal of Physical Chemistry C
- 出版年：2010
- 出版时间：November 11, 2010
- 年：2010
- 卷：114
- 期：44
- 页码：19024-19034
- 全文大小：569K
- 年卷期：v.114,no.44(November 11, 2010)
- ISSN：1932-7455
文摘
Anhydrous Keggin-type phosphorus heteropolyacids were deposited on partially dehydroxylated silica by using the surface organometallic chemistry (SOMC) strategy. The resulting solids were characterized by a combination of physicochemical methods including IR, Raman, 1D and 2D 1H, and 31P MAS NMR, electron microscopy experiments and density functional theory (DFT) calculations. It is shown that the main surface species is [≡Si(OH...H+)]2[H+]1[PM12O403−] where the polyoxometalate is linked to the support by proton interaction with two silanols. Two other minor species (10% each) are formed by coordination of the polyoxometalate to the surface via the interaction between all three protons with three silanol groups or via three covalent bonds formed by dehydroxylation of the above species. Comparison of the reactivity of these solids and of compounds prepared by a classical way shows that the samples prepared by the SOMC approach contain ca. 7 times more acid sites.