Morphogenesis of Shapes in Mesoporous Molecular Sieves

• Main Authors: Meng-Ta Chou, 周孟達
• Other Authors: Yu-Wen Chen
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/14341047531273597271

碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 90 === A neutral templating route to mesoporous molecular sieves has been reported by Pinnavaia based on hydrogen bonding interactions and self-assembly between neutral primary amine micelles and neutral inorganic precursors. The effect of cosolvent on the morphology of HMS is still not clear. Hexagonal mesoporous silica (HMS) was prepared at ambient temperature by using dodecylamine (DDA) as the template and tetraethyl orthosilicate (TEOS) as a silica derivative in this study. The properties of HMS were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and N2 adsorption/desorption. The morphology of HMS is usually irregular and small particle. To investigate the morphological change of this HMS material, the samples prepared at various TEOS adding rate, solvent compositions and compositions were studied. With decreasing TEOS adding rate, the sizes of HMS particles increase and the textural porosity reduces. With the concentration of DDA reduces, HMS particles become crackled bigger particles from small particles and the pore size reduces from 2.32nm to 1.72 nm. As [DDA]=0.0159 M, the spherical particles of HMS silicas with uniform size and isolated are obtained. Besides, TEOS adding rate also affects the size of the spheroids. The noodle-like structures are prepared in HMS silicas prepared at R/H ratio=0. These noodle-like structures were about 0.1μm in diameter and about submicrometer to several micrometers in length. In a series of HMS silicas synthesized by various [TEOS], the irregular trends indicated that it is required to prepare the samples under non-alcoholic solution to have non-spherical particles. However, some other parameters may also play a role.