Evolution of standing mesochannels on porous anodic alumina substrates with designed conical holes

We report the formation of standing mesochannels simply by spin-coating a precursor solution onto a PAA (porous anodic alumina) substrate with designed conical holes, utilizing exactly the same precursors and reaction conditions that form two-dimensional (2D) hexagonal mesoporous SBA-15-type films. When the aspect ratios of the conical holes are lower, the sponge-like mesopores are generated within the conical holes. Such a formation of sponge-like mesostructures truly acts as a trigger for the evolution of perpendicularly oriented and tilted mesochannels. On the other hand, when the PAA substrates with high-aspect cones are used, the mesochannels are stacked like a doughnut within the conical holes, which leads to parallel orientations of the mesochannels in the continuous film region.     

Synthesis of highly ordered mesoporous crystalline WS(2) and MoS(2) via a high-temperature reductive sulfuration route

A high-temperature reductive sulfuration method is demonstrated to synthesize highly ordered mesoporous metal sulfide crystallites by using mesoporous silica as hard templates. H2S gas is utilized as a sulfuration agent to in situ convert phosphotungstic acid H3PW12O40.6H2O to hexagonal WS2 crystallites in the silica nanochannels at 600 degrees C. Upon etching silica, mesoporous, layered WS2 nanocrystal arrays are produced with a yield as high as 96 wt %. XRD, nitrogen sorption, SEM, and TEM results reveal that the WS2 products replicated from the mesoporous silica SBA-15 hard template possess highly ordered hexagonal mesostructure (space group, p6mm) and rodlike morphology, analogous to the mother template. The S-W-S trilayers of the WS2 nanocrystals are partially oriented, parallel to the mesochannels of the SBA-15 template. This orientation is related with the reduction of the high-energy layer edges in layered metal dichalcogenides and the confinement in anisotropic nanochannels. The mesostructure can be 3-D cubic bicontinuous if KIT-6 (Iad) is used as a hard template. Mesoporous WS2 replicas have large surface areas (105-120 m2/g), pore volumes ( approximately 0.20 cm3/g), and narrow pore size distributions ( approximately 4.8 nm). By one-step nanocasting with the H3PMo12O40.6H2O (PMA) precursor into the mesochannels of SBA-15 or KIT-6 hard template, highly ordered mesoporous MoS2 layered crystallites with the 2-D hexagonal (p6mm) and 3-D bicontinuous cubic (Iad) structures can also be prepared via this high-temperature reductive sulfuration route. When the loading amount of PMA precursor is low, multiwalled MoS2 nanotubes with 5-7 nm in diameter can be obtained. The high-temperature reductive sulfuration method is a general strategy and can be extended to synthesize mesoporous CdS crystals and other metal sulfides.     

Strategic synthesis of SBA-15 nanorods

A simple synthesis of homogeneously sized, ordered mesoporous silica nanorods (SBA-15), spanning about 10 porous channels in width and ranging from 300 to 600 nm in length is reported.     

Synthesis of N‐Doped Mesoporous Carbon Nanorods through Nano‐Confined Reaction: High‐Performance Catalyst Support for Hydrogenation of Phenol Derivatives

Traditional hard‐template methods for the preparation of mesoporous carbon structures have been well developed, but there are difficulties associated with complete filling of the organic precursors in ordered mesochannels and exact replication of the templates. Herein, mesoporous carbon nanorods (meso‐CNRs) were synthesized through thermal condensation of furfuryl alcohol followed by the nano‐confined decomposition of polyfurfuryl alcohol in silica nanotubes (SiO₂ NTs) with porous shells. Limited and slow release of gaseous water through the porous shells and finite polyfurfuryl precursor inside silica nanotubes are responsible for the formation of the mesoporous structures. Nitrogen can be doped into the meso‐CNRs by adding guanidine hydrochloride to the precursors. The nitrogen dopant not only stabilizes the ultrasmall and active Pd nanocatalyst in the meso‐CNRs but also increases the electron density of Pd and accelerates the dissociation of H₂, both of which increase the catalytic activity of the Pd catalyst in hydrogenation reactions.     

由纳米晶前驱体组装有序介孔silicalite-1分子筛

采用两步法将不同尺寸的silicalite-1分子筛纳米晶种通过自组装合成了一系列有序介孔silicalite-1分子筛。首先将强碱性的silicalite-1前驱体分别加热不同时间得到纳米晶种,然后在类似合成SBA-15的强酸性条件下组装成有序的介孔材料。合成条件的剧烈变化阻止了分子筛晶种的继续长大,并在三嵌段共聚物模板的诱导下组装成有序介孔材料。这种“自下而上”的方法制备有序介孔分子筛同时包含微孔和介孔。氮气吸脱附结果表明所制备的介孔分子筛材料均表现了很大的比表面积(730 m2/g以上)。     

Controlled growth of mesostructured crystalline iron oxide nanowires and Fe-filled carbon nanotube arrays templated by mesoporous silica SBA-16 film

The three-dimensional (3D) accessible pore structures (Imm space groups) of continuous mesoporous silica SBA-16 thin films have been prepared by a dip-coating technique in nonaqueous media under acidic conditions on indium-tin oxide glass (ITO). The films are oriented with the (111) crystal plane perpendicular to the surface of the film. On one hand, deposition of iron metal into the mesopores of SBA-16 films was achieved by using an electrochemical method. The Fe2O3 nanowire arrays were synthesized. The crystalline structures of porous Fe2O3 nanowires and nanorods were studied via TEM, SEM, and XRD. On the other hand, a small amount of Fe was deposited into the pores of the SBA-16 thin film as a catalyst, and carbon nanotube arrays formed inside the pores of SBA-16 film were fabricated by catalytic decomposition of acetylene at 700 degrees C. The second-order template synthesis method for preparing the ordered array of carbon nanotubes filled with Fe has been used. The carbon nanotubes are very uniform in diameter and length and are aligned vertically with respect to the SBA-16 film.     

介孔分子筛SBA-15中α-胰凝乳蛋白酶组装及催化活性研究

介孔分子筛由于规则孔道或笼的存在 ,使其具有择形催化作用、高比表面积和强吸附性能 ,其孔道中可组装多种物质而改变其理化性能 .Thomas等 [1] 在介孔 Si O2 上接枝金属茂复合物 .白妮 [2 ] 和张雪峥 [3 ] 等分别将脂溶性金属酞菁衍生物和杂多酸封装在介孔分子筛中 ,得到的组装体催化性能优良 .近年来由于不断合成出 MCM- 41 [4 ] 和 SBA- 1 5 [5] 等孔径较大的介孔分子筛 ,使在介孔材料孔道中组装生物大分子成为可能 .Yen等 [6] 将细胞色素 c组装到孔道中 ,并使酶的稳定性得到提高 ,而α-胰凝乳蛋白酶 (Mr=2 5 0 0 0 ,分子动力学直径…     

Deoxycholate as an efficient coating agent for hydrophilic silicon nanocrystals

A layer of macrocyclic calix[4]arene derivatives has been grafted on the internal surface of the mesochannels of the ordered mesoporous SBA-15 to develop highly efficient trap for heavy transition metal (HTM) ions. To ensure the successful anchoring of calix[4]arene derivatives on the surface of SBA-15, two different types of calix[4]arene derivatives, one with one trimethoxysilane functional group and another with two trimethoxysilane functional groups have been explored. XRD, N(2) adsorption and TEM results provide strong evidence that the mesoporous structure of the supporting materials retain their long range ordering throughout the grafting process. Solid-state NMR, TG and FT-IR spectroscopy indicate that both types of calix[4]arene derivatives can be well-anchored on the surface of the wall of SBA-15. Calix[4]arene derivative with only one trimethoxysilane functional group showed high grafting efficiency compared to that with two trimethoxysilane functional groups due to the intramolecular and intermolecular polycondensation between two trimethoxysilane functional groups. The HTM ions extraction capacity in aqueous solution of macrocycle functionalized SBA-15 nanohybrides for a series of HTM ions has been studied. The obtained materials demonstrated very high HTM ions extraction capacity up to 96% for Pb(2+) in aqueous solution.     

Highly efficient enrichment and subsequent digestion of proteins in the mesoporous molecular sieve silicate SBA-15 for matrix-assisted laser desorption/ionization mass spectrometry with time-of-flight/time-of-flight analyzer peptide mapping

Based on a previous study of protein digestion inside the nanoreactor channels of the mesoporous molecular sieve silicate SBA-15 (Chem. Eur. J. 2005, 11: 5391), we have developed a highly efficient enrichment and subsequent tryptic digestion of proteins in SBA-15 for matrix-assisted laser desorption/ionization mass spectrometry with time-of-flight/time-of-flight analyzer (MALDI-TOF/TOF) peptide mapping. The performance of the method is exemplified with myoglobin and cytochrome c. First, protein adsorption isotherms for two standard proteins with a range of initial concentration of proteins were investigated at room temperature. The results revealed that the kinetic adsorption rate of a protein within SBA-15 was independent of initial protein concentration, and a 15-min protein enrichment within SBA-15 could be enough for protein identification in biological samples. It was noticed that no washing steps were needed to avoid protein loss due to desorption from the mesochannels into solution. Second, protein digestion inside the channels of SBA-15 was also optimized. After adsorption of proteins into SBA-15 in 15 min, the trypsin solution (pH 8) was directly added to the SBA-15 beads with immobilized proteins by centrifugation, and then the digestion was performed for 15 min at 37 degrees C. It was observed that a higher peptide sequence covering of 98% for myoglobin was obtained by MALDI-TOF/TOF analysis, compared to in-solution digestion. So the protein digestion inside SBA-15 was proved to be significantly faster and yielded a better sequence coverage. The new procedure allows for rapid protein enrichment and digestion inside SBA-15, and has great potential for protein analysis.     

A family of ordered mesoporous carbons derived from mesophase pitch using ordered mesoporous silicas as templates

A variety of ordered mesoporous carbons (OMCs) were synthesized using ordered mesoporous silicas (OMSs) as hard templates and the mesophase pitch (MP) as a carbon precursor. The synthesis included the mixing of OMS with MP, the infiltration of OMS with MP at 450–550?°C and the carbonization of MP in OMS/MP composite followed by the dissolution of the OMS template. OMCs with structures of two-dimensional hexagonal arrays of nanorods and three-dimensional arrays of nanospheres were obtained through the replication of silica templates, including large-pore SBA-15, KIT-6, large-pore FDU-12 and SBA-16. In particular, 2-D hexagonal array of carbon nanorods (CMK-3 carbon) with (100) interplanar spacing of ～13 nm as well as an array of carbon nanospheres arranged in the face-centered cubic structure with the unit-cell parameter of 33 nm were successfully prepared. The specific surface areas of the resulting carbons were up to 400 m²/g, and the total pore volumes were up to 0.43 cm³/g, with the highest values achieved when the MP infiltration temperature was 500?°C. The OMCs exhibited narrow mesopore size distributions. As inferred from XRD, the frameworks of OMCs featured semi-graphitic structures even though moderate carbonization temperature (850?°C) was employed.     

富含羧基的球形介孔分子筛SBA-15的合成及药物释放性能

本文采用原位合成法合成了富含羧基的SBA-15球形介孔分子筛. 研究了修饰剂（三烷氧基氰乙基硅烷 CTES）的用量对介孔分子筛SBA-15形貌、孔径及BET比表面积的影响. 用粉末X射线衍射(XRD)、扫描电镜(SEM)、红外（IR）和氮气吸附/脱附对样品进行了详细的表征. 该材料展示了尺寸在0.5-1 μm规则的球形形貌、有序的二维六方相介孔结构、较大的比表面积和孔容、并且随着修饰剂用量的增加, SBA-15的孔径变小, 比表面积下降. 药物组装及缓释性能测试表明, 该材料具有较好的药物组装及缓释释放性能. 该材料在催化、药物载体和色谱分析填料等领域将具有潜在的应用.     

Synthesis and magnetic investigation of ordered mesoporous two-line ferrihydrite

We report here for the first time on the synthesis and characterization of ordered mesoporous two-line ferrihydrite. Ordered mesoporous ferrihydrite has been prepared via the nanocasting route. Two types of ordered mesoporous silica, two-dimensional hexagonal SBA-15 and three-dimensional cubic KIT-6, were employed as hard templates. The magnetic behavior of ferrihydrite replicas with an average diameter of about 7 nm was investigated by direct current magnetometry. The temperature dependence of magnetization shows a superparamagnetic transition around 70 K. Field-induced changes in the low-field behavior of the magnetization were observed below 30 K. The results are explained assuming a spin-glass-like state of the surface spins. The 2D hexagonal two-line ferrihydrite showed very large coercivity up to 1.6 kOe at 5 K.     

SBA-15的孔壁碳膜修饰对钴基催化剂结构与催化性能的影响

在惰性气体中焙烧SBA-15制得孔壁被碳修饰的SBA- 15C样品,以它和SBA-15为载体,采用等量浸渍法制备了负载型Co基催化剂,并运用X射线衍射、N2物理吸附、程序升温还原、NH3吸附量热等手段对样品进行了表征.结果表明,SBA- 15C仍保持原有的六方有序的中孔结构,但其孔壁经碳修饰后发生增厚,比表面积略有下降...     

Immobilization of chiral oxazaborolidine catalyst over highly ordered 3D mesoporous silica with Ia3d symmetry for enantioselective reduction of prochiral ketone

Here we demonstrate for the first time the encapsulation of a chiral oxazaborolidine complex in the 3D mesoporous channels of an amine functionalized KIT-6 material via covalent bonding through a post-synthetic approach. The physico-chemical properties of the pure and immobilized KIT-6 catalysts were obtained by various techniques such as XRD, nitrogen adsorption, HRSEM, UV-Vis diffuse reflectance spectroscopy, and FT-IR spectroscopy. It has been found that the structural stability of the KIT-6 was not affected even after the immobilization of a significant amount of chiral ligand inside the mesoporous channels of the support. However, the values of structural parameters such as the specific surface area and the specific pore volume of the KIT-6 support was significantly lower than the pure KIT-6 support. The chemical interaction between the chiral ligand inside the mesochannels and the KIT-6 support was also confirmed by UV-Vis and FT-IR spectroscopy. The chiral catalytic performance of the immobilized catalysts for the enantioselective reduction of aromatic prochiral ketones was demonstrated and the results were compared with chiral catalyst immobilized supports with uni-dimensional porous structures, such as MCM-41 and SBA-15. Among the catalysts studied, chiral catalyst immobilized KIT-6 showed the highest performance with a high product yield and a high enantioselectivity due to its 3D porous structure with two continuous and interpenetrating systems of chiral channels and an interwoven 3D cylindrical type pores of Ia3d symmetry. The catalyst also exhibited much better recycling capability than other chiral catalyst supported mesoporous materials used in the study.     

Structure and diffusion characterization of SBA-15 materials

In situ formation of the micro- and mesoporous structures of SBA-15 materials was investigated. It was found that the structure is significantly different from that for cylindrical or hexagonal pores, which suggests that the SBA-15 is more complex than an array of hexagonally ordered channels. Nitrogen adsorption isotherms at 77 K provided evidence that large (primary) mesopores are accompanied by a certain amount of significantly smaller pores with a broad distribution in the micropore/small-mesopore range within the mesoporous walls of main channels. It was found that the microporosity can be controlled by the time of heating as well as the synthesis temperature. The diffusion properties of n-heptane as a probe molecule in four selected SBA-15 samples with different micropore volumes were studied by the standard zero length column technique and related to their structural characteristics. The results have shown that the diffusion process involving n-heptane at a low concentration level takes place inside the walls of main mesoporous channels and depends on the relative content of micropores. In the samples that have a relatively high content of micropores, n-heptane diffusivities are relatively low, their activation energies are high, and the process is similar to diffusion in typical microporous adsorbents, like zeolites. As the micropore content is decreased, diffusion becomes more and more controlled by secondary mesopores of the intrawall pore structure, rendering diffusion faster and activation energies lower.     

Synthesis of mesoporous carbons using ordered and disordered mesoporous silica templates and polyacrylonitrile as carbon precursor

Mesoporous carbons were synthesized from polyacrylonitrile (PAN) using ordered and disordered mesoporous silica templates and were characterized using transmission electron microscopy (TEM), powder X-ray diffraction, nitrogen adsorption, and thermogravimetry. The pores of the silica templates were infiltrated with carbon precursor (PAN) via polymerization of acrylonitrile from initiation sites chemically bonded to the silica surface. This polymerization method is expected to allow for a uniform filling of the template with PAN and to minimize the introduction of nontemplated PAN, thus mitigating the formation of nontemplated carbon. PAN was stabilized by heating to 573 K under air and carbonized under N2 at 1073 K. The resulting carbons exhibited high total pore volumes (1.5-1.8 cm3 g(-1)), with a primary contribution of the mesopore volume and with relatively low microporosity. The carbons synthesized using mesoporous templates with a 2-dimensional hexagonal structure (SBA-15 silica) and a face-centered cubic structure (FDU-1 silica) exhibited narrow pore size distributions (PSDs), whereas the carbon synthesized using disordered silica gel template had broader PSD. TEM showed that the SBA-15-templated carbon was composed of arrays of long, straight, or curved nanorods aligned in 2-D hexagonal arrays. The carbon replica of FDU-1 silica appeared to be composed of ordered arrays of spheres. XRD provided evidence of some degree of ordering of graphene sheets in the carbon frameworks. Elemental analysis showed that the carbons contain an appreciable amount of nitrogen. The use of our novel infiltration method and PAN as a carbon precursor allowed us to obtain ordered mesoporous carbons (OMCs) with (i) very high mesopore volume, (ii) low microporosity, (iii) low secondary mesoporosity, (iv) large pore diameter (8-12 nm), and (v) semi-graphitic framework, which represent a desirable combination of features that has not been realized before for OMCs.     

Preparation, Characterization and Catalytic Performance of La-SO42-/SBA-15 in Esterification of Acetic Acid with n-Butanol

La-SO42-/SBA-15 was synthesized with various amounts of lanthanum via incipient-wetness impregnation.Characterization was done by X-ray diffraction(XRD), transmission electron micrographs(TEM), nitrogen adsorption,FTIR spectroscopic analysis, thermogravimetric analysis, and the total amount of acidity of catalyst was estimated by TPD of NH3. The results indicate that lanthanum has been incorporated into SBA-15 molecular sieve. The prepared materials(La-SO42-/SBA-15) keep the highly ordered mesoporous two-dimensional hexagonal structure and do not change the mesoporous channel structure of the support SBA-15. The catalyst showed best catalytic activity in the synthesis of n-butyl acetate. The optimum conditions of the esterification by orthogonal experiments were studied: the molar ratio of n-butanol to acetic acid 1:1.2, the amount of catalyst 7.5%, reaction time 80 min. The yield of n-butyl acetate could reach 93.2% under the optimum conditions. The catalyst was recyclable, cost effective and environmental friendly.     

铝修饰改性对SBA-15分子筛性质及催化剂性能的影响

分别采用调变pH值合成法和后处理嫁接法制备了铝修饰改性的SBA-15分子筛,通过XRD、Al核磁、N₂吸附脱附、NH₃-TPD等方法对改性分子筛的理化性质进行了分析表征,考察了不同的Al修饰改性方法对分子筛性质和加氢裂化催化剂性能的影响。结果表明,调变pH值合成法能够有效地对SBA-15进行Al改性,得到的Al-SBA-15分子筛具有高度有序的六方孔道结构,较好的水热稳定性。Al的引入提高了SBA-15的表面酸性,并使其在加氢裂化反应中表现出较好的中油选择性。     

Post-synthesis deposition of V-zeolitic nanoparticles in SBA-15

A post-synthesis deposition of vanadium silicalite-1 zeolite nanoparticles in the pores of SBA-15 results in a highly ordered hexagonal templated silica material with V-silicalite zeolitic plugs, giving rise to an increased crystallinity of the amorphous mesoporous walls.     

水热一步法合成Ti-SBA-15分子筛及其催化性能研究

采用钛酸丁酯和乙酰丙酮作用后的产物作为钛的前驱体，水热法一步合成出了 Ti-SBA-15分子筛。通过X射线衍射、N2气吸附脱附、紫外—可见漫反射等表征手段 ，证明在Si/Ti＝50，25，20时，钛原子成功地取代了SBA-15中的硅原子而没有改 变SBA-15高度有序的介孔二维六角结构，其中钛全部以四配位状态存在，而且高度 分散。当Si/Ti＝12．5时，钛的分散度降低，部分钛聚集生成二氧化钛。与用两步 法合成的Ti-SBA-15比较，一步法合成的Ti-SBA-15中钛分散度好，添加量高，对催 化氧化环己烯有较高的催化活性。对一步法和两步法合成Ti-SBA-15的机理以及相 应产物在结构以及催化活性上的差异进行了探讨。