共查询到20条相似文献,搜索用时 15 毫秒
1.
Low-temperature strategy to synthesize highly ordered mesoporous silicas with very large pores 总被引:5,自引:0,他引:5
Fan J Yu C Lei J Zhang Q Li T Tu B Zhou W Zhao D 《Journal of the American Chemical Society》2005,127(31):10794-10795
By employing a novel low-temperature synthetic pathway, highly ordered cubic mesoporous materials with hitherto the largest pores (up to 27 nm) and unit cells (up to 44 nm) have been successfully obtained. 相似文献
2.
Monodisperse spherical periodic mesoporous organosilicas (PMOs) with ethane integrated in the framework were synthesized and their application as stationary phase for chromatographic separation is demonstrated. The ethane-PMOs were prepared by condensation of 1,2-bis(triethoxysilyl)ethane (BTSE) in basic condition using octadecyltrimethylammonium chloride (C(18)TMACl) as template and ethanol as co-solvent. The morphology and mesoporous structure of ethane-PMOs were controlled under different concentrations of sodium hydroxide (NaOH) and EtOH. The results of scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), nitrogen sorption measurement, Fourier transform infrared spectroscopy (FT-IR) and elemental analysis showed that ethane-PMOs have spherical morphology, uniform particle distribution, highly ordered pore structure, high surface area and narrow pore-size distribution. The column packed with these materials exhibits good permeability, high chemical stability and good selectivity of mixtures of aromatic hydrocarbons in normal phase high-performance liquid chromatography (HPLC). 相似文献
3.
F. Fakhfakh L. Baraket J. M. Fraile J. A. Mayoral A. Ghorbel 《Journal of Sol-Gel Science and Technology》2009,52(3):388-397
Hybrid mesoporous silicas functionalized with ethylenediamine groups have been synthesized via sol–gel process under different conditions. The best textural properties, with pore diameters up to 170 Å, have been obtained using carboxylic acids as catalysts in propanol as solvent without the need for any surfactant. The presence of the diamine moiety has been demonstrated by different characterization techniques, and the materials have been used in the adsorption of copper cations. The adsorption capacity of all the solids is high (up to 1.87 mmol/g and up to 2.47 Cu atoms/nm2), with important variations in the properties of the silica surface, besides the role of the immobilized diamine moieties as ligand for copper. In general the surface area seems to be the most important feature controlling the adsorption. 相似文献
4.
Periodic mesoporous organosilica with a heterocyclic bridging group of large molecular weight, tris[3-(trimethoxysilyl)propyl]isocyanurate, is reported. Incorporation of an organic moiety into the silica framework afforded material attractive for adsorption of mercury and related heavy metal ions from aqueous solutions. 相似文献
5.
I. S. Berezovska V. V. Yanishpolskii V. A. Tertykh 《Journal of Thermal Analysis and Calorimetry》2008,94(3):649-653
Template syntheses of mesoporous silicas have been carried out inside large pores of inorganic matrix. Portions of tetraethoxysilane
and cetyltrimethylammonium bromide micellar solution were incorporated step-by-step inside pore volume of silica gel with
large pore size. Synthesized materials were characterized using thermal analysis, adsorption-desorption of nitrogen and X-ray
diffraction scattering. 相似文献
6.
Xueao Zhang Jianfang Wang Wenjian Wu Changli Liu Siwen Qian 《Journal of Sol-Gel Science and Technology》2007,43(3):305-311
Highly ordered amino-functionalized mesoporous silica thin films have been directly synthesized by co-condensation of tetraethoxysilane
(TEOS) and 3-aminopropyltriethoxysilane (APTES) in the presence of triblock copolymer Pluronic P123 surfactant species under
acidic conditions by sol-gel dip-coating. The effect of the sol aging on thin films organization is systematically studied,
and the optimal sol aging time is obtained. The amino-functionalized mesoporous silica thin films exhibit a long-range ordering
of 2D hexagonal (p6mm) mesostructure with a large pore size of 8.3 nm, a large Brunauer–Emmett–Teller (BET) specific surface area of 680 m2 g−1 and a large pore volume of 1.06 cm3 g−1 following surfactant extraction as demonstrated by X-ray diffraction (XRD), Transmission electron microscope (TEM), and physical
adsorption techniques. Based on BET surface area and weight loss, the surface coverage of amino-groups for the amino-functionalized
mesoporous silica thin films is calculated to be 3.2 amino-groups per nm2. Moreover, the functionalized thin films display improved properties for immobilization of cytochrome c in comparison with pure-silica mesoporous thin films. 相似文献
7.
Highly ordered three-dimensional Im3m-type periodic mesoporous organosilica with a cavity size of 9.8 nm has been synthesized under strongly acidic media in the presence of inorganic salts using triblock copolymer F127 as the template and 1,2-bis(trimethoxysilyl)ethane as the organically bridged silica source. 相似文献
8.
Huang F Zheng Y Li Z Xiao Y Zheng Y Cai G Wei K 《Chemical communications (Cambridge, England)》2011,47(18):5247-5249
Highly dispersed ceria-zirconia supported on ordered mesoporous alumina, showing higher thermal stability up to 900 °C, has been successfully synthesized via a sol-gel process associated with P123 as the template in ethanol solvent. 相似文献
9.
Yang Y Lim S Du G Chen Y Ciuparu D Haller GL 《The journal of physical chemistry. B》2005,109(27):13237-13246
Highly ordered Ni-MCM-41 samples with nearly atomically dispersed nickel ions were prepared reproducibly and characterized. Similar to the Co-MCM-41 samples, the pore diameter and porosity can be precisely controlled by changing the synthesis surfactant chain length. Nickel was incorporated by isomorphous substitution of silicon in the MCM-41 silica framework, which makes the Ni-MCM-41 a physically stable catalyst in harsh reaction conditions such as CO disproportionation to single wall carbon nanotubes or CO2 methanation. X-ray absorption spectroscopy results indicate that the overall local environment of nickel in Ni-MCM-41 was a tetrahedral or distorted tetrahedral coordination with surrounding oxygen anions. Hydrogen TPR revealed that our Ni-MCM-41 samples have high stability against reduction; however, compared to Co-MCM-41, the Ni-MCM-41 has a lower reduction temperature, and both the H2-TPR and in situ XANES TPR reveal that the reducibility of nickel is not clearly correlated with the pore radius of curvature, as in the case of Co-MCM-41. This is probably a result of nickel being thermodynamically more easily reduced than cobalt. The stability of the structural order of Ni-MCM-41 has been investigated under SWNT synthesis and CO2 methanation reaction conditions as both require catalyst exposure to reducing environments leading to formation of metallic Ni clusters. Nitrogen physisorption and XRD results show that structural order was maintained under both SWNT synthesis and CO2 methanation reaction conditions. EXAFS results demonstrate that the nickel particle size can be controlled by different prereduction temperatures but not by the pore radius of curvature as in the case of Co-MCM-41. 相似文献
10.
Matos JR Kruk M Mercuri LP Jaroniec M Zhao L Kamiyama T Terasaki O Pinnavaia TJ Liu Y 《Journal of the American Chemical Society》2003,125(3):821-829
FDU-1 silicas with large cage-like pores (diameter about 10 nm) were synthesized under acidic conditions from tetraethyl orthosilicate in the presence of a poly(ethylene oxide)-poly(butylene oxide)-poly(ethylene oxide) triblock copolymer template B50-6600 (EO(39)BO(47)EO(39)). High-resolution transmission electron microscopy and small-angle X-ray scattering provided strong evidence that FDU-1 silica synthesized under typical conditions is a face-centered cubic Fm3m structure with 3-dimensional hexagonal intergrowth and is not a body-centered cubic Im3m structure, as originally reported. Samples synthesized in a wide range of conditions (initial temperatures from 298 to 353 K; hydrothermal treatment at 333-393 K) exhibited similar XRD patterns and their nitrogen adsorption isotherms indicated a good-quality cage-like pore structure. The examination of low-pressure nitrogen adsorption isotherms for FDU-1 samples, whose pore entrance diameters were evaluated using an independent method, allowed us to conclude that low-pressure adsorption was appreciably stronger for samples with smaller pore entrance sizes. This prompted us to examine low-pressure adsorption isotherms for a wide range of samples and led us to a conclusion that the FDU-1 pore entrance size can be systematically enlarged from about 1.3 nm (perhaps even lower) to at least 2.4 nm without an appreciable loss of uniformity by increasing the temperature of the hydrothermal treatment or the initial synthesis. Further enlargement of pore entrance size was achieved for sufficiently long hydrothermal treatment times at temperatures of 373 K or higher, as seen from the shape of nitrogen desorption isotherms. This allowed us to obtain samples with uniform pore sizes, high adsorption capacity, and with pore entrances enlarged so much that their size was similar to the size of the pore itself, resulting in a highly open porous structure. However, in the latter case, there was evidence that the pore entrance size distribution was quite broad. 相似文献
11.
Well ordered bridged organosilica highly functionalised with disulfide groups were obtained by self-assembly of alpha,omega-bis(trimethoxysilyl)alkyldisulfide under hydrophilic conditions; the reduction of disulfide cores to SH groups gave rise to material having a high mercury ion adsorption capacity. 相似文献
12.
Highly ordered mesoporous inorganic-organic hybrid thin films with covalently bonded carboxylic acid (-COOH) terminal groups on the pore surfaces were synthesized by evaporation induced self-assembly of tetraethoxysilane, organosilanes, and a nonionic surfactant followed by acid hydrolysis and characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, surface acoustic wave (SAW) based N2 sorption, and thermogravimetric analysis (TGA) techniques. 相似文献
13.
Tanaka N Mizoshita N Maegawa Y Tani T Inagaki S Jorapur YR Shimada T 《Chemical communications (Cambridge, England)》2011,47(17):5025-5027
A novel spirobifluorene-bridged allylsilane precursor, which can be easily purified by silica gel chromatography, was prepared by using a new molecular building block for allylsilane sol-gel precursors (MBAS) and successfully converted into a highly fluorescent periodic mesoporous organosilica film. 相似文献
14.
A new procedure to seal the pores of mesoporous low-k films with precondensed organosilica oligomers
Goethals F Baklanov MR Ciofi I Detavernier C Van der Voort P Van Driessche I 《Chemical communications (Cambridge, England)》2012,48(22):2797-2799
A new strategy to seal mesoporous low-k thin films with a pore size of 3 nm has been developed. This is achieved by spin-coating of a self-assembled carbon-bridged organosilica layer followed by a grafting with hexamethyl disilazane. 相似文献
15.
Morishige K Tateishi M Hirose F Aramaki K 《Langmuir : the ACS journal of surfaces and colloids》2006,22(22):9220-9224
To verify pore blocking controlled desorption in ink-bottle pores, we measured the temperature dependence of the adsorption-desorption isotherms of nitrogen on four kinds of KIT-5 samples with expanded cavities hydrothermally treated for different periods of time at 393 K. In the samples, almost spherical cavities are arranged in a face-centered cubic array and the cavities are connected through small channels. The pore size of the channels increased with an increase in the hydrothermal treatment time. At lower temperatures a steep desorption branch changed to a gradual one as the hydrothermal treatment was prolonged. For the sample hydrothermally treated only for 1 day, the rectangular hysteresis loop shrank gradually with increasing temperature while keeping its shape. The temperature dependence of the evaporation pressure observed was identical with that expected for cavitation-controlled desorption. On the other hand, for the samples hydrothermally treated for long times, the gradual desorption branch became a sharp one with increasing temperature. This strongly suggests that the desorption mechanism is altered from pore blocking to cavitation with temperature. Application of percolation theory to the pore blocking controlled desorption observed here is discussed. 相似文献
16.
Periodic mesoporous organosilicas (PMOs) were prepared by cooperative assembly with corresponding organosilane precursors
in the presence of surfactants. Recently, approaches for the preparation of a new class of porphrin-bridged PMOs have been
developed. Porphyrin-bridged PMOs were synthesized by direct co-condensation using a thermal sol–gel method or a rapid microwave-assisted
method with tetrakis(carboxyphenyl)porphyrin(TCPP)-silsesquioxane (TCPPS) and various silica sources in the presence of templates.
These porphyrin PMO exhibited high catalytic activities and selectivity and could be used repeatedly in many kinds of applications
owing to easy accessibility, rapid diffusion, and favorable mass transfer for substrates into and out of the mesopores. In
addition, the TCPPS incorporated into the PMO walls could effectively defend damage of the ordered structure and also inhibit
the leaching of active sites. The current review deals with recent development in the synthesis, characterization, and applications
such as hydrogenation, photocatalysis, chiral catalysis, and Baeyer–Villiger oxidation of each of these types of porphyrin-bridged
periodic mesoporous silica materials. 相似文献
17.
Highly ordered rod-like large-pore periodic mesoporous organosilica (PMO) was successfully synthesized at low acid concentration with the assistance of inorganic salt using triblock copolymer P123 as a template. The roles of inorganic salt and acidity in the production of highly ordered mesostructure and the morphology control of PMOs were investigated. It was found that the inorganic salt can significantly widen the range of the synthesis parameters to produce highly ordered 2D hexagonal pore structure of p6mm symmetry. However, the uniform rod-like PMOs can only be synthesized in a narrow range of acid and salt concentrations, which were sensitive to induction time. The adsorption of lysozyme on PMO was studied at different pH values in comparison with adsorption on pure silica material under controlled morphology and pore structure. It was found that the adsorption capacity of lysozyme on the PMO was lower than that on pure SBA-15 silica material and the adsorption amounts are larger at pH 9.6 than at 7.0 for both materials. The results show that the electrostatic interaction between lysozyme and PMO/SBA-15 surface is more dominant than the hydrophobic forces and the interaction of neighboring lysozyme molecules also plays an important role. 相似文献
18.
Synthesis and photocatalytic properties of highly crystalline and ordered mesoporous TiO2 thin films 总被引:1,自引:0,他引:1
Tang J Wu Y McFarland EW Stucky GD 《Chemical communications (Cambridge, England)》2004,(14):1670-1671
Highly crystalline and ordered mesoporous TiO2 thin films have been synthesized by stabilization of the mesostructure with confined carbon; the films exhibit 2.5% photoconversion efficiency for the water photolysis at zero-bias and Xe lamp illumination of 40 mW cm(-2). 相似文献
19.
Natalya A. Vodolazkaya Christelle Despas Bénédicte Lebeau Claire Marichal Alain Walcarius 《Journal of Sol-Gel Science and Technology》2012,63(3):587-594
New hybrid organic–inorganic materials exhibiting ordered mesoporous structures have been synthesized by co-condensation of tetraethoxysilane and various alkyltrimethoxysilanes with increasing length of the hydrocarbon chain (propyl, octyl, hexadecyl), in water–ethanol solution containing ammonia, in the presence of a cationic surfactant (cetyltrimethylammonium bromide) as templating agent. The obtained hybrid materials were characterized by using several physico-chemical techniques, such as X-ray diffraction, N2 adsorption, 29Si MAS NMR, SEM and elemental analysis. It was shown that the direct synthesis procedure allows obtaining ordered hybrid mesoporous silica with various contents of organic functions, from 5 to 20 %. Moreover, increasing the chain length of the organic group, from propyl to octyl and hexadecyl leads to a change of the pore structure from hexagonal p6mm MCM-41 type architecture to cubic Ia3d MCM-48 type mesostructure. 相似文献
20.
Highly ordered mesoporous titania films consisting of crystalline nanopillars with open-spaced, perpendicular, and continuous porosity have been prepared via structural transformation from a 3D hexagonal mesostructure during the thermal treatment. The mechanism of the structural transformation is explained by the crystallization of the titania framework and the large contraction of the initial 3D hexagonal mesostructured film upon calcination. This structural transformation provides a new approach to generate mesoporous thin-film materials with unique structures. 相似文献