Mesoporous materials with uniform pores and high specific areas are used in many fields including catalysts, separation and adsorbents, etc. In order to find faster and more economical synthesis routes, the use of mic...Mesoporous materials with uniform pores and high specific areas are used in many fields including catalysts, separation and adsorbents, etc. In order to find faster and more economical synthesis routes, the use of microwave heating was deeply studied. Compared to the hydrothermal method, microwave energy can heat the samples to crystallization temperature rapidly and uniformly result in homogeneous nucleation and shorten crystallization time. The basic principles of microwave assisted synthesis and advantages of microwave heating, and the obtained progress concerning ordered mesoporous materials through microwave synthesis were summarized.展开更多
Novel in-situ reduction approach was applied for the synthesis of palladium nanoparticles in the pores of mesoporous silica materials with grafted siliconhydride groups. Matrices possessing different structural proper...Novel in-situ reduction approach was applied for the synthesis of palladium nanoparticles in the pores of mesoporous silica materials with grafted siliconhydride groups. Matrices possessing different structural properties (MCM-41, SBA-15 and Silochrom) were used. Samples were studied by nitrogen adsorption-desorption method, low-angle X-ray diffraction, transmission electron microscopy (TEM) and FT-IR/PAS spectroscopy. The temperature-programmed oxidation (TPO) and reduction (TPR) methods were applied to examine reducibility of palladium species. Palladium containing catalysts were tested in methane oxidation reaction. It was demonstrated that relatively large pores in SBA-15 type silica facilitated formation of well-dispersed palladium nanoparticles confined in the pores channels. In the case of MCM-41 support, metallic palladium nanoparticles were formed on the external surface. The obtained materials showed high catalytic activity. Lower activity of the samples containing small crystallites located in the pore volume at high temperatures was related to worse accessibility of active sites to the reation mixture.展开更多
分别以高分子三嵌段共聚物P123(PEO20-PPO70-PEO20)和F127(PEO106-PPO70-PEO106)为模板剂,通过高温水热法制备了具有超低介电常数的规则介孔氧化硅材料(OMSs).当合成温度达到200℃时,得到的产物仍可保持规则的介孔结构.X射线衍射和氮气...分别以高分子三嵌段共聚物P123(PEO20-PPO70-PEO20)和F127(PEO106-PPO70-PEO106)为模板剂,通过高温水热法制备了具有超低介电常数的规则介孔氧化硅材料(OMSs).当合成温度达到200℃时,得到的产物仍可保持规则的介孔结构.X射线衍射和氮气吸附结果表明,OMSs系列材料具有规则的二维六方或体心立方介孔结构、大的比表面积和孔容及均一的孔径分布.29Si MAS NMR分析表明,OMSs与低温(100℃)合成产物相比具有更高的骨架缩合度,从而具有优异的水热稳定性.由于具有大的孔容和高的骨架缩合度,OMSs表现出了超低的介电常数.以P123为模板剂,200℃下合成的OMS的介电常数可达1.31.OMSs作为一类稳定的超低介电常数材料,对于绝缘材料的发展具有潜在的应用价值.展开更多
Octa(tetramethylammonium)-polyhedral oligomeric silsesquioxane(TMA-POSS) with cage-like structure was synthesized, the structure was characterized by NMR, FTIR and Elemental analyses. The mesoporous silica was prepare...Octa(tetramethylammonium)-polyhedral oligomeric silsesquioxane(TMA-POSS) with cage-like structure was synthesized, the structure was characterized by NMR, FTIR and Elemental analyses. The mesoporous silica was prepared under alkaline condition using TMA-POSS as the silicon source and hexadecyltrimethylammonium bromide (CTAB) as the template, the structures of these products were characterized by XRD, TEM and nitrogen adsorption and desorption methods. The results indicate that the synthesized silica exhibites a well-ordered hexagonal pore structure with larger specific surface area. With increasing of CTAB molar ratio, the spacing of the crystal plane d100 is increased. The effects of the pH values on the mesoporous structure in the reaction system with different molar ratio of nPOSS / nCTAB were investigated. The synthesis mechanism of mesoporous silica was also discussed.展开更多
Ordered mesoporous silica inorganic films were prepared in an acid solution at the air-solution interface by the biomimetic synthesis method, during which the hydrolysis of tetraethoxy silane (TEOS) was directed by ce...Ordered mesoporous silica inorganic films were prepared in an acid solution at the air-solution interface by the biomimetic synthesis method, during which the hydrolysis of tetraethoxy silane (TEOS) was directed by cetyltrimethyl ammonium bromide (CTAB) supramolecule self-assemblies. The effects of material ratio, pH and sampling time on the qualities of silica films were investigated. Fourier transform infrared (FTIR) spectrophotometer, High resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) were used to measure the biomimetic synthesized silica films extracted with 0.50 mol·L-1 hydrochloric acid ethanol solution. The results indicate that the structure of hexagonal ordered mesoporous is maintained, while the surfactant is removed effectively in mesoporous silica films.展开更多
基金Project(20775096/B050104) supported by the National Natural Science Foundation of ChinaProject(20080440696) supported by China Postdoctoral Science Foundation
文摘Mesoporous materials with uniform pores and high specific areas are used in many fields including catalysts, separation and adsorbents, etc. In order to find faster and more economical synthesis routes, the use of microwave heating was deeply studied. Compared to the hydrothermal method, microwave energy can heat the samples to crystallization temperature rapidly and uniformly result in homogeneous nucleation and shorten crystallization time. The basic principles of microwave assisted synthesis and advantages of microwave heating, and the obtained progress concerning ordered mesoporous materials through microwave synthesis were summarized.
基金This work was supported by European Community,seventh Framework Programm(FP/2007-2013)Marie Curie International Research Staff Exchange Scheme(grant no.230790)project MEC 06 MAT2006 01997.
文摘Novel in-situ reduction approach was applied for the synthesis of palladium nanoparticles in the pores of mesoporous silica materials with grafted siliconhydride groups. Matrices possessing different structural properties (MCM-41, SBA-15 and Silochrom) were used. Samples were studied by nitrogen adsorption-desorption method, low-angle X-ray diffraction, transmission electron microscopy (TEM) and FT-IR/PAS spectroscopy. The temperature-programmed oxidation (TPO) and reduction (TPR) methods were applied to examine reducibility of palladium species. Palladium containing catalysts were tested in methane oxidation reaction. It was demonstrated that relatively large pores in SBA-15 type silica facilitated formation of well-dispersed palladium nanoparticles confined in the pores channels. In the case of MCM-41 support, metallic palladium nanoparticles were formed on the external surface. The obtained materials showed high catalytic activity. Lower activity of the samples containing small crystallites located in the pore volume at high temperatures was related to worse accessibility of active sites to the reation mixture.
文摘分别以高分子三嵌段共聚物P123(PEO20-PPO70-PEO20)和F127(PEO106-PPO70-PEO106)为模板剂,通过高温水热法制备了具有超低介电常数的规则介孔氧化硅材料(OMSs).当合成温度达到200℃时,得到的产物仍可保持规则的介孔结构.X射线衍射和氮气吸附结果表明,OMSs系列材料具有规则的二维六方或体心立方介孔结构、大的比表面积和孔容及均一的孔径分布.29Si MAS NMR分析表明,OMSs与低温(100℃)合成产物相比具有更高的骨架缩合度,从而具有优异的水热稳定性.由于具有大的孔容和高的骨架缩合度,OMSs表现出了超低的介电常数.以P123为模板剂,200℃下合成的OMS的介电常数可达1.31.OMSs作为一类稳定的超低介电常数材料,对于绝缘材料的发展具有潜在的应用价值.
文摘Octa(tetramethylammonium)-polyhedral oligomeric silsesquioxane(TMA-POSS) with cage-like structure was synthesized, the structure was characterized by NMR, FTIR and Elemental analyses. The mesoporous silica was prepared under alkaline condition using TMA-POSS as the silicon source and hexadecyltrimethylammonium bromide (CTAB) as the template, the structures of these products were characterized by XRD, TEM and nitrogen adsorption and desorption methods. The results indicate that the synthesized silica exhibites a well-ordered hexagonal pore structure with larger specific surface area. With increasing of CTAB molar ratio, the spacing of the crystal plane d100 is increased. The effects of the pH values on the mesoporous structure in the reaction system with different molar ratio of nPOSS / nCTAB were investigated. The synthesis mechanism of mesoporous silica was also discussed.
文摘Ordered mesoporous silica inorganic films were prepared in an acid solution at the air-solution interface by the biomimetic synthesis method, during which the hydrolysis of tetraethoxy silane (TEOS) was directed by cetyltrimethyl ammonium bromide (CTAB) supramolecule self-assemblies. The effects of material ratio, pH and sampling time on the qualities of silica films were investigated. Fourier transform infrared (FTIR) spectrophotometer, High resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) were used to measure the biomimetic synthesized silica films extracted with 0.50 mol·L-1 hydrochloric acid ethanol solution. The results indicate that the structure of hexagonal ordered mesoporous is maintained, while the surfactant is removed effectively in mesoporous silica films.
