- 學位論文
含金屬矽酸鹽SBA-15及奈米尺寸中孔洞材料之合成鑑定及應用
Synthesis, Characterization and Application of Metallosilicate SBA-15 and Nanoscale Mesoporous Materials.
摘要
A series of gallosilicate SBA-15 nanoporous materials with different Si/Ga molar ratios were synthesized using a novel method of controlling the TMAOH/Ga mole ratios in gel. The amount of gallium incorporated into structure, the pore size and the pore volume of the GaSBA-15 porous material increase with TMAOH/Ga mole ratio. More than 85 % of Ga is 4-coordinated and incorporated into the framework of the SBA-15 product as revealed by 71Ga MAS NMR spectra. Brönsted acid sites in GaSBA-15 are more abundant than that in GaMCM-41. Higher concentrations of Brönsted acid sites on GaSBA-15 surface and fast diffusion in its large pore channel may contribute to its high cumene-crackingcatalytic activity. Amount of aluminum directly incorporated into SBA-15 materials can be governed simply by various hydrothermal temperatures and time in mild acid solution without any tedious procedures. More than 90 % of aluminum in all products except sample with nSi/nAl of 5 is four-coordinated which is evidenced by 27Al solid-state NMR and thus is incorporated directly into SBA-15 framework. Aluminosilicate SBA-15 containing higher Al contents owns better hexagonal structural order than siliceous SBA-15 or other with lower Al contents at pH2.5. It is probably due to additional interaction between aluminosilicate Brönsted acid site with P123 surfactant. A range of nanoscale aluminosilicate and gallosilicate mesoporous molecular sieves could be prepared using microwave hydrothermal techniques without tedius procedures. These nanoscale nanoporous materials own high surface area, pore volume, narrow pore size distribution and nano-particle size between 20 and 100 nm and four-coordinated aluminum or gallium site mainly. Mesoporosity, mesostructure and nanosize can be controlled simply by the temperature and time of microwave irradiation. Acidity of nanoscale one is stronger than that of conventional one and acid sites for nanoscale one is more abundant than that of conventional one with medium acidic strength. Higher concentrations of external surface sites and fast diffusion for nanoscale porous particle may contribute to their high catalytic activity. Covalently bonded nanoscale mesoporous silica (NMS)/polyimide novel nanocomposites have been synthesized through the bridge of 3-aminopropyltrimethoxysilane (APTMS). Abundant reactive amino-functional groups inside the mesopore channels of NMS can interconnect with several polyimide main chains, and thus multi-linked and complex NMS/PI networks are formed. These effective multi-linkages, NMS inherent nanoporsity and well dispersion of NMS in polyimide result that thermal stable, mechanical, elongation, moisture absorption and dielectric constant properties of these novel materials are significantly improved as compared with neat polyimide. Reducing dielectric constants of polyimide could be caused by the nanoporosity in the core of the NMS materials and external void between the polyimide matrix and NMS. The dielectric constant of composites with variable amounts of NMS correlates closely with their respective density related to the nanoporosity of NMS. Polyimide main chains have hydrogen bonding and van der Waals forces not only with surface polar molecules of NMS particle but also with channel surface molecules due to the polymer intrusion into NMS nanopores. Therefore, the polymer network has enhanced mechanical and thermal properties.
並列摘要
A series of gallosilicate SBA-15 nanoporous materials with different Si/Ga molar ratios were synthesized using a novel method of controlling the TMAOH/Ga mole ratios in gel. The amount of gallium incorporated into structure, the pore size and the pore volume of the GaSBA-15 porous material increase with TMAOH/Ga mole ratio. More than 85 % of Ga is 4-coordinated and incorporated into the framework of the SBA-15 product as revealed by 71Ga MAS NMR spectra. Brönsted acid sites in GaSBA-15 are more abundant than that in GaMCM-41. Higher concentrations of Brönsted acid sites on GaSBA-15 surface and fast diffusion in its large pore channel may contribute to its high cumene-crackingcatalytic activity. Amount of aluminum directly incorporated into SBA-15 materials can be governed simply by various hydrothermal temperatures and time in mild acid solution without any tedious procedures. More than 90 % of aluminum in all products except sample with nSi/nAl of 5 is four-coordinated which is evidenced by 27Al solid-state NMR and thus is incorporated directly into SBA-15 framework. Aluminosilicate SBA-15 containing higher Al contents owns better hexagonal structural order than siliceous SBA-15 or other with lower Al contents at pH2.5. It is probably due to additional interaction between aluminosilicate Brönsted acid site with P123 surfactant. A range of nanoscale aluminosilicate and gallosilicate mesoporous molecular sieves could be prepared using microwave hydrothermal techniques without tedius procedures. These nanoscale nanoporous materials own high surface area, pore volume, narrow pore size distribution and nano-particle size between 20 and 100 nm and four-coordinated aluminum or gallium site mainly. Mesoporosity, mesostructure and nanosize can be controlled simply by the temperature and time of microwave irradiation. Acidity of nanoscale one is stronger than that of conventional one and acid sites for nanoscale one is more abundant than that of conventional one with medium acidic strength. Higher concentrations of external surface sites and fast diffusion for nanoscale porous particle may contribute to their high catalytic activity. Covalently bonded nanoscale mesoporous silica (NMS)/polyimide novel nanocomposites have been synthesized through the bridge of 3-aminopropyltrimethoxysilane (APTMS). Abundant reactive amino-functional groups inside the mesopore channels of NMS can interconnect with several polyimide main chains, and thus multi-linked and complex NMS/PI networks are formed. These effective multi-linkages, NMS inherent nanoporsity and well dispersion of NMS in polyimide result that thermal stable, mechanical, elongation, moisture absorption and dielectric constant properties of these novel materials are significantly improved as compared with neat polyimide. Reducing dielectric constants of polyimide could be caused by the nanoporosity in the core of the NMS materials and external void between the polyimide matrix and NMS. The dielectric constant of composites with variable amounts of NMS correlates closely with their respective density related to the nanoporosity of NMS. Polyimide main chains have hydrogen bonding and van der Waals forces not only with surface polar molecules of NMS particle but also with channel surface molecules due to the polymer intrusion into NMS nanopores. Therefore, the polymer network has enhanced mechanical and thermal properties.
參考文獻
延伸閱讀
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- 王宏丞（2005）。Direct Microwave Synthesis and Characterization of Three-Dimensional metallosilicate SBA-16 nanoporous materials〔碩士論文，中原大學〕。華藝線上圖書館。https://doi.org/10.6840/cycu200500507