Adsorption of methanol on mesoporous SBA-15

The adsorption of methanol on mesoporous SBA-15 has been studied by using Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The BET surface area analysis shows decreases of the surface area from 387 to 383 m²/g, pore volume from 0.88 to 0.81 cm³/g and pore diameter from 9.07 to 8.4 nm after methanol adsorption. The appearance of strong IR bands at 2862 and 2964 cm^− 1 due to methyl (-CH₃) symmetric and asymmetric stretching demonstrate the presence of methanol and evidence of successful methanol adsorption. XPS results show increase of carbon and oxygen content on the surface of SBA-15. Thermogravimetric analysis shows that the methanol adsorbed on SBA-15 is stable up to a temperature of 265 °C and that the methanol adlayers decompose between 265 and 588 °C.     

Pd-porphyrin functionalized ionic liquid-modified mesoporous SBA-15: An efficient and recyclable catalyst for solvent-free Heck reaction

The Pd-porphyrin functionalized ionic liquid could be covalently anchored in the channels of mesoporous SBA-15 through ion-pair electrostatic interaction between imidazolium-cationic and Pd-porphyrin-anionic moieties. Such modified SBA-15 materials were prepared successfully via a post-synthesis (surface sol-gel polymerization) or a one-pot sol-gel procedure, which were characterized by powder X-ray diffraction, UV-visible spectroscopy, Fourier transform infrared spectroscopy, N₂ sorption, elemental analysis, and transmission electron microscopy. The modified SBA-15 materials are efficient and recyclable catalysts for cross-coupling of aryl iodides or activated aryl bromides with ethyl acrylate without activity loss and Pd leaching even after 9 runs.     

A novel approach for synthesizing ordered mesoporous silica SBA-15

Ordered SBA-15 with a high specific surface area, large pore size and pore volume could be synthesized at a short time (overnight) without further calcination. During the SBA-15 synthesis process, TEOS hydrolysis, the condensation of the silica species and the decomposition of the Pluronic P123 template were completed by using sulphuric acid. The decomposed Pluronic P123 could be completely exacted by solvent after synthesis. SBA-15 had high hydrothermal stability.     

改性SBA-15介孔脱硫剂

通过超声波辅助后合成方法制备了一种新型Fe2O3担载SBA-15硅酸盐介孔材料,并于室温条件下进行了材料的0.1％硫化氢气体的脱硫实验.研究了Fe2O3的化学特性和材料的结构特性对脱硫性能的影响.使用氮吸附、X射线衍射、X射线能谱、透射电子显微镜、电感耦合等离子体发射光谱等方法对脱硫实验前后的材料进行了表征.结果显示,...     

Crossed-discs of mesoporous silica SBA-15 and their carbon replicas

Crossed-discs of mesoporous silica SBA-15 were synthesized by using tetramethylorthosilicate (TMOS) as silica source in the presence of Sn²⁺ cations. The silica crossed-discs were characterized by small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption. All the results show that the materials have hexagonally ordered channels running parallel to the thickness of the discs. The effects of the reaction conditions on the morphology of the materials were discussed. The SBA-15 crossed-discs were used as hard templatesto obtain their carbon replicas.     

Simultaneous synthesis of modified Binol-periodic mesoporous organosilica SBA-15 type material. Application as catalysts in asymmetric sulfoxidation reactions

The synthesis of a chiral periodic mesoporous organosilica (chiral PMO) SBA-15 type, using a bis-silylated Binol precursor, has been studied through two different heterogenization routes. On the one hand, the immobilization of a (R)-(+)-1,1′-bi-2-naphthol (Binol) derivative was accomplished by following a standard multistep synthesis methodology. On the other hand, a new route consisting of an easy one-step synthesis was developed achieving a simultaneous formation of mesoporous structure and Binol chiral ligand immobilization in the walls. The addition of KCl “salting out” electrolytes favored the micellization, obtaining the well-ordered chiral PMO materials. The thioanisole asymmetric oxidation reaction was used to validate the enantio-catalysts activity. The materials synthesized by the multistep method reached yield and enantiomeric excess of 41 and 15 %, respectively, while the synthesized one-pot chiral PMO materials achieved up to 58 and 42 %, respectively. This difference could be attributed to a more homogenous distribution of the chiral moiety as well as the simultaneous micellization and formation of the siliceous mesostructure, in the one-pot procedure. This promotes higher reagents accessibility to the active center, and therefore an enhancement of the chiral induction. Thereby, materials with Binol ligand incorporated into the three-dimensional silica framework were successfully accomplished.     

pH值敏感介孔纳米复合材料SBA-15/PAA的制备与性能研究

通过浸渍吸附的方法将pH值敏感的功能单体-丙烯酸引入到介孔二氧化硅SBA-15的孔道内,经自由基聚合使丙烯酸(AA)在孔道内聚合,成功合成了pH值敏感的SBA-15/聚丙烯酸(PAA)纳米复合材料,所得纳米复合材料的结构通过XRD、TEM、氮气吸附/脱附、TG、FT-IR等手段进行了表征,并进行了pH敏感性能研究.结果表明,当聚合物(PAA)的量达到20%左右时,复合材料仍然具有较大的孔体积0.5203cm3/g和较高的比表面积334.5m2/g.聚合反应的发生没有破坏SBA-15的有序介孔结构,这种纳米复合材料初步显示出了pH敏感性.这种具有高比表面的pH值响应介孔纳米复合材料,有望在药物缓释领域得到应用.     

Template synthesis of boron nitride nanotubes in mesoporous silica SBA-15

Nitride nanotubes (BN-NTs) was synthesized by chemical vapor deposition (CVD) using BCl₃ and NH₃ at relatively low temperature within the channels of mesoporous silica SBA-15. TEM images confirmed the existence of BN-NTs. The BN-NTs were of uniform diameter about 7 nm, which was consistent with the channel diameter of the template SBA-15. Using this approach, it is easy to control the diameter of BN-NTs by adjusting the diameter of the channel of mesoporous silica host.     

功能化SBA-15介孔材料的制备及其吸附性能研究

硅基介孔材料因其特有的特性,被用于去除废水中重金属离子的吸附剂.为了提高对目标污染物的吸附容量, 本文采用一步法和两步法制备了氨基或巯基功能化SBA-15介孔材料,利用傅里叶红外光谱仪、场发射扫描电镜、X射线衍射仪和氮气吸附脱附表征测试了材料的化学组成、微观形貌和物相结构.测试结果显示经功能化处理后的样品成功地接枝氨基或巯基功能基团.研究发现,经功能化处理后,材料的骨架结构及介孔孔道均未被破坏,但有序性下降且出现少许团聚,物性参数也有一定程度下降,功能化材料对Zn²⁺、Pb²⁺、Cr³⁺和Cu²⁺的吸附率均有大幅度提高.经氨基或巯基功能化后,SBA-15介孔材料对水体中重金属离子的吸附率有很大提高,但一步法制备的功能化硅基介孔材料因模板剂去除不彻底而影响了对重金属离子的吸附效率,两步法制备的功能化硅基介孔材料对重金属离子的吸附效果更好,说明本文的功能化硅基介孔材料工艺是可行有效的,但两步法合成的功能化介孔材料具有更好的吸附效果.     

Improved luminescence properties of europium complexes encapsulated into mesoporous SBA-15

Two kinds of Eu3+ COmplexes-Eu(TTA)3(TPPO)2 (TTA: thenoyltrifluoroacetone, TPPO: triphenylphosphineoxide) and Eu(BA)3(TPPO)2 (BA: 1-benzoylacetone)-were fully encapsulated, uniformly distributed into the channels of unmodified and modified SBA-15, and structurally characterized. The luminescent properties of the encapsulated complexes were systematically studied in contrast to the pure complexes. The results indicate that the excitation bands assigned to the pi-pi* electron transition of the ligands for Eu3+ complexes encapsulated in SBA-15 were split into different components, and the 5D0-7F0 transitions became partly allowed. The emission lines for the 5D0-7F2 transitions became broader and the relative intensity for different crystal field components varied greatly in comparison to the pure complex. Most importantly, the photostability and thermostability of the emissions improved considerably.     

Short-period synthesis of ordered mesoporous silica SBA-15 using ultrasonic technique

Mesoporous silica SBA-15 was synthesized from rice husk ash via the ultrasonic technique in the hydrolysis-condensation stage. The effect of the time period in this stage on the mesoporous silica SBA-15 structure and physical properties was investigated and compared with those of the SBA-15 prepared by the conventional technique. It has been shown that the ultrasonic technique can be successfully applied for the synthesis of mesoporous silica SBA-15 with highly ordered hexagonal pore-arrangement and narrow PSD within the much shorter hydrolysis-condensation period. The SBA-15 products synthesized via the ultrasonic technique for the time period of 3 h have higher specific surface area, total pore volume, and microporosity than those prepared by the conventional technique for the time period of 24 h.     

Design and synthesis of Alq3-functionalized SBA-15 mesoporous material

A luminescent organic molecule aluminum tris(8-hydroxyquinoline) (Alq₃) has been successfully introduced in the pores of amino-functionalized mesoporous SBA-15 (APS-SBA-15). An obvious blue-shifted photoluminescence (PL) of Alq₃ was observed. In the pores of APS-SBA-15, the Alq₃ organic molecules exhibited efficient and intense PL as monomers and the emission intensities increased with increasing Alq₃ concentration.     

Improving bioavailability of silybin by inclusion into SBA-15 mesoporous silica materials

Mesoporous silica SBA-15 (SC) and template occluded SBA-15 (SP) were used to increase the bioavailability of silybin, an extremely poorly water soluble drug. Silybin was introduced into SC and SP by assembling or self-assembling methods. The results of X-ray powder diffraction, differential scanning calorimetry (DSC) and N2 adsorption-desorption experiment indicated that amorphous silybin was successfully introduced into the mesopores in both SC and SP samples. The transmission electron micrograph (TEM) images revealed that the structure of the mesoporous materials was not destroyed after the drug loading. Results of dissolution rate tests and animal experiments showed that both SC and SP can significantly improve the bioavailability of silybin, SP was thus preferred because the template needs not to be removed by calcination or extraction.     

纳米颗粒磁增强SBA-15介孔复合材料的制备及磁性能

利用浸渍法合成了Co₃O₄/SBA-15和CoFe₂O₄/SBA-15介孔纳米磁性材料, 并利用X射线粉末衍射(XRD)、 透射电子显微镜(TEM)、 场发射扫描电子显微镜(FESEM)及振动样品磁强计(VSM)对样品的微观结构和磁性能进行了分析。结果显示, Co₃O₄及CoFe₂O₄纳米颗粒分布在SBA-15介孔材料的孔道中, 可有效提高SBA-15介孔材料的磁性能。研究发现, SBA-15介孔纳米磁性材料的磁特性由掺杂的纳米磁性颗粒的性质决定, 其磁性能随Co₃O₄及CoFe₂O₄含量的增加而升高, 矫顽力可达400Oe, 饱和磁化强度达9emu/g。      

Morphological control on SBA-15 mesoporous silicas via a slow self-assembling rate

Pluronic 123-templated mesoporous SBA-15 silica rods with a length of ca. 3.0–4.0 μm were easily synthesized in a dilute silicate solution with a pH value of 2.0 at room temperature. Through a good control on the synthetic condition and the chemical components, a high homogeneity (>95%) of the hexagonal SBA-15 silica rods can be achieved. In addition, the effect of the synthetic conditions including acid source, weight ratio of the P123/sodium silicate, temperature, water content, pH value, and applying shearing flow were explored in detail to tailor the morphologies of the SBA-15 mesoporous silicas. In this paper, we also focused on the counterion effect on the synthesis of the SBA-15 mesoporous silicas. It was found that the SO₄ ²⁻ counterion from H₂SO₄ has higher affinity to induce the formation of P123 rod-like micelles than that of Cl⁻, NO₃ ⁻. Meanwhile, we postulated that the self-assembly pathway of the silica species and the neutral tri-block copolymer micelles in a dilute solution with a pH value of 2.0 would occur through an S⁰···I⁰ rather than the S⁰X^−…I⁺ one as previously discussed. We further employed the SAB-15 mesoporous silica rods as the templates to synthesize high-quality CMK-3 mesoporous carbon rods by using commercially available phenol–formaldehyde (PF) resin as the carbon source.     

Synthesis of mixed-phase uniformly infiltrated SBA-3-like in SBA-15 bimodal mesoporous silica from rice husk ash

The mixed-phase bimodal mesoporous silicas (BMS) were simply synthesized via sol-gel technique using rice husk ash-derived sodium silicate as a silica source, and Pluronic P123 and cetyltrimethyl ammonium bromide (CTAB) as the pore structure-directing agents. The gel solution composition in the synthesis process was based on SiO₂:Pluronic P123:CTAB:HCl:H₂O molar ratio of 1:0.088:0.088:4:200. The effect of mixing sequences of starting materials on BMS structures was investigated. The phase separation among SBA-15, SBA-3-like porous silica and xerogel was found when the gel solutions of SBA-15 and SBA-3-like were prepared separately in the primary stage, whereas the mixed-phase uniformly infiltrated SBA-3-like in SBA-15 bimodal porous silica was successfully synthesized when CTAB was added into the SBA-15 gel solution and the secondary micelle structure was formed inside the primary SBA-15 framework.     

酸度对掺杂Ce-SBA-15介孔分子筛合成的影响

采用溶胶-凝胶法,以三嵌段共聚物(P123)作为模板剂,正硅酸乙酯(TEOS)为硅源,通过微波辅助加热快速合成出骨架掺杂的Ce-SBA-15介孔分子筛.采用X射线粉末衍射(XRD)、傅立叶变换红外(FT-IR)、N2等温吸附-脱附法、紫外-可见漫反射(DRS)等手段对合成的样品进行表征.结果表明,当凝胶的pH=2～7时...     

Photocatalytic properties of the SBA-15 mesoporous silica molecular sieve modified with titanium

We describe three methods of post-synthesis modification of the SBA-15 mesoporous molecular sieve with titanium: impregnation with Ti(OEt)₄ in an ethanolic solution, grafting with titanocene dichloride, and modification with colloidal titania. The products were characterized using X-ray diffraction (XRD) and N₂ adsorption as well as Fourier-transform infrared and ²⁹Si NMR spectroscopies. All three methods yield materials containing 1.4--4.7 wt.% titanium and with high surface areas. The absorbance at 960 cm⁻¹ in SBA-15 modified with colloidal titania and SBA-15 grafted with titanocene indicates the formation of Ti–O bonds. All products showed significant activity towards the degradation of p-chlorophenol. UV-vis absorption spectra of SBA-15 samples modified with titanium indicate that the variation in the photocatalytic activity is governed by isolated titanium sites.     

Synthesis and properties of dense bulks for mesoporous silica SBA-15 by a modified hydrothermal method

Dense SBA-15 bulks with mesoporous structure as well as powdered SBA-15 were successfully synthesized by the modified hydrothermal method. These SBA-15 bulks have the higher density of 1.16 to 1.19 g/cm³, compared to green density of 0.68 g/cm³ for the pellet from SBA-15 powder. Obtained SBA-15 bulks possessed extremely high BET surface area of 467 m²/g and mesopore of 4.0 nm in diameter The possibility of densification for SBA-15 bulks using this method was confirmed.