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Preparation and Characterization of Porous Oxide Spherical Particles

Author: ZhaoLi
Tutor: YuJiaGuo
School: Wuhan University of Technology
Course: Materials Physics and Chemistry
Keywords: porous SiO2 microspheres SiO2/TiO2 composite microspheres SiO2/Al2O3 composite microspheres electrostatic attraction hard template TiO2 nanometer crystal
CLC: TB383.4
Type: PhD thesis
Year: 2006
Downloads: 910
Quote: 2
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Abstract


The development of mesoporous silica materials by researchers of Mobil Corporation in 1992 stimulated explosive research on the preparation of porous materials through templates approaches. In this thesis, we focused on the preparation of monodispersed SiO2 microspheres with high specific surface area, and then oxide particles deposited on the surface of the as-prepared SiO2 microspheres by two main chemical methods to obtain monodispersed oxide composite microspheres with core/shell structures. The effects of experimental conditions and methods on particle size, morphology and microstructure of composite microspheres were investigated and discussed as main tasks in this paper.This thesis was divided into five major parts. The first part reported the synthesis of monodispersed microporous silica microspheres by hydrolysis and condensation of tetraethoxysilane （TEOS） using alkylamine as template. The results showed that the alkyl chain length of 1-alkylamine obviously influenced the morphologies and sizes of SiO2 particles. With increasing the alkyl chain length of 1-alkylamine, the pore volume and average pore size increased, however, surface area decreased. The quality of the silica microspheres synthesized using hexadecylamine and octadecylamine as templates were inferior to that of the silica microspheres synthesized using dodecylamine as a template. The optimal synthesis conditions were as follows: [TEOS] = 0.11-0.18 mol L-1, [DDA] = 0.016-0.24 mol L-1 and hydrolysis temperature = 15°C. The small angle XRD and HRTEM results confirmed that the prepared SiO2 microspheres had disordered pore structuresIn part 2, monodispersed porous SiO2/TiO2 composite microspheres with high specific surface areas were prepared by depositing titania colloid particles on the surface of monodispersed microporous silica microspheres using a simple electrostatic attraction strategy. Uniform titania coatings could be deposited on the surface of silica microspheres by adjusting the pH value of the reaction solution to a optimal pH value ranges of about 3-5. The specific surface area and pore volume of the SiO2/TiO2 composite microspheres calcined at 600°C were 960 m2g-1 and 0.48 mLg-1, respectively.In part 3, SiO2/TiO2 composite microspheres with microporous core/mesoporous

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