Synthesis of High Surface Area Phosphosilicate Glasses by a Modified Sol-Gel Method
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- 作者：Antonio Aronne ; Maria Turco ; Giovanni Bagnasco ; Pasquale Pernice ; Martino Di Serio ; Nigel J. Clayden ; Elisa Marenna ; and Esther Fanelli
- 刊名：Chemistry of Materials
- 出版年：2005
- 出版时间：April 19, 2005
- 年：2005
- 卷：17
- 期：8
- 页码：2081 - 2090
- 全文大小：186K
- 年卷期：v.17,no.8(April 19, 2005)
- ISSN：1520-5002
文摘
High surface area phosphosilicate glasses were synthesized by a new sol-gel method and characterizedfor structural, textural, and acid properties by X-ray diffraction, thermogravimetry/differential thermalanalysis, IR spectroscopy (Fourier transform and diffuse reflectance Fourier transform), solid state 31Pand 29Si NMR spectroscopy, N2 adsorption, and NH3 temperature programmed desorption. The glasseswere synthesized by a sol-gel route hydrolyzing the precursors in an almost solely aqueous environment.Microstructural changes occurring during the conversion of the gels into the corresponding glasses wereinvestigated. For all dried gels (383 K), the elimination of organic residues was complete at 673 K. Afterthis heat treatment, ca. 80% of the phosphorus was present as free phosphoric acid except for the samplewith the highest P content for which the percentage dropped to ca. 47%. Textural properties of samplestreated at 673 K were greatly influenced by the composition. Surface area decreased and pore dimensionincreased with increasing phosphorus content, indicating a gradual transformation of the siloxane matrixfrom microporous to mesoporous. Br
nsted acid sites of differing strength, mainly related to the presenceof phosphoric acids, were found. The surface concentration and strength of acid sites increased withphosphorus content.
nsted acid sites of differing strength, mainly related to the presenceof phosphoric acids, were found. The surface concentration and strength of acid sites increased withphosphorus content.