CMC和CTAB双模板法合成具有稳定结构的MCM-41中孔分子筛

以羧甲基纤维素和十六烷基三甲基溴化铵为双模板,制备出了具有更高稳定性并且具有高度有序二维六方结构的MCM-41介孔分子筛.透射电镜和X射线衍射结果表明,以双模板制备的MCM-41介孔分子筛具有高度有序的二维六方(p6mm)孔道结构.此外,以双模板制备的MCM-41介孔分子筛焙烧前后的X射线衍射结果表明,在焙烧过程中其晶胞收缩比例为3.1%.与以纯表面活性剂为模版制备的MCM-41介孔分子筛(晶胞收缩比例为9.7%)相比,双模板制备的MCM-41介孔分子筛具有更高的稳定性能. MCM-41介孔分子筛稳定性能的提高可能是由于在硅物种、表面活性剂以及羧甲基纤维素在自组装过程中,羧甲基纤维素表面丰富的羟基与硅物种Si-(OH)x的相互作用促进了Si-(OH)x的缩聚.     

MCM-41介孔分子筛共价键联钴酞菁的制备，表征及性质

采用两种方法将钴酞菁配合物共价联接到介孔分子筛MCM-41的表面：(1) 在MCM-41表面联接含伯胺的有机侧链；(2) 是在MCM-41表面联接含仲胺的有机侧链。含氯磺酸基的钴酞菁与胺反应形成磺酰胺。对得到的主客体化合物用多种物化手段和催化反应进行了表征。结果表明，钴酞菁以单体形式固定在介孔分子筛MCM-41的孔道壁上，在反应条件下固载后的钴酞菁具有高催化活性，同时表现出良好的稳定性，多次重复使用活性没有明显的改变。     

以混合表面活性剂为模板可控合成MCM-48和MCM-41分子筛

利用阳离子和三嵌段共聚物混合表面活性剂为模板,在水热条件、碱性介质中可控合成出MCM-48和MCM-41分子筛。在固定P123(聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物):TEOS(正硅酸乙酯)(物质的量的比)为0.01875的体系中,调节CTAB(十六烷基三甲基溴化铵)∶TEOS(正硅酸乙酯)物质的量比值m,当m在0.12~0.13范围合成出MCM-48分子筛;当m在0.04~0.08范围合成出MCM-41分子筛。通过XRD,TEM,N2物理吸附,IR等方法进行了表征。结果表明:聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物(P123)的加入可以更大程度地降低合成介孔材料所需阳离子表面活性剂的用量;可控合成的介孔材料具有高比表面积、高度有序的孔道结构、较集中的孔径分布。     

超分子模板法合成层状中孔结构氧化铝

利用烷基硫酸钠作为模板剂在室温下合成了层状中孔结构氧化铝,考察了表面活性剂碳链长度和表面活性剂混合比例对层状氧化铝中孔相结构参数的影响.当使用单一表面活性剂作为模板剂时,层状中孔结构氧化铝的层间距d及其层状结构的长程有序度随着表面活性剂碳链长度的增加而增加;若使用C₈H₁₇SO₄Na与C₁₄H₂₉SO₄Na混合表面活性剂作为混合模板剂,当C₁₄H₂₉SO₄Na摩尔分数x处在0～0.5时,层间距基本恒定,接近于具有二者平均碳链长度(n=11)的单一表面活性剂作为模板剂时的情形;当x>0.5时,层间距随x的增大而逐渐增大.通过提出的混合表面活性剂在无机层中的分子排列结构模型对该结果做了解释.     

磺酸基团功能化的碳-硅介孔复合材料的制备及其在生物柴油绿色合成中的应用(英文)

利用化学浸渍法将蔗糖负载到 SBA-15 介孔材料孔道内部, 高温炭化形成的多聚苯环经发烟硫酸气相磺化处理后, 得到磺酸基团功能化的新型碳-硅介孔复合材料. 发烟硫酸气相磺化处理是该材料合成的关键步骤. X 射线衍射、扫描电镜和氮气吸附结果表明, 碳-硅介孔复合材料经磺酸化处理保持了高度有序的介孔结构. 热重、傅里叶变换的红外光谱及吡啶吸附红外光谱结果证明, 磺酸功能基团成功的嫁接于碳-硅介孔复合材料孔道的内表面, 反应活性中心为 Br?nsted 酸, 酸密度在 0.09~0.70 mmol/g 可以有效调变. 当碳负载量为 35% 时, 该复合材料在生物柴油的绿色合成中显示出最优的催化性能, 且可重复使用 3 次以上.     

Ti-Si介孔分子筛的转晶与控制

以季铵盐型阳离子Gemini表面活性剂[C16H33(CH3)2N+(CH2)6N+(CH3)2C16H33]•2Br−(GEM16-6-16)为模板剂, 改变n(Ti)/n(Si)比值, 合成了系列Ti-Si介孔分子筛. X射线衍射(XRD)和透射电子显微镜(TEM)等表征结果表明, 在n(Ti)/n(Si)≤0.20时, 分子筛为高度有序六方介孔; 当 n(Ti)/n(Si)为 0.30时, 介孔转晶为立方相; 当n(Ti)/n(Si)为0.50时, 介孔转晶为层状相; n(Ti)/n(Si)为1.0时, 材料失去有序孔道结构. FT-IR分析表明, 在分子筛骨架间形成了Ti—O—Si键, 而且Ti—O—Si键的数目随n(Ti)/n(Si)的增加而增加, 达到一定饱和值后基本保持不变. 乙醇和丁醇对纯硅基介孔分子筛孔结构转晶控制作用呈现六方相→立方相→层状相递变规律, 因而钛酸正丁酯水解生成的丁醇对Ti-Si介孔分子筛转晶具有一定的控制作用.     

具有可控分散性的不同粒径氨基酸双功能化介孔二氧化硅纳米颗粒

通过表面活性剂,共结构导向剂（CSDAs）和硅源的自组装合成了具有分散性的不同粒径氨基酸双功能化介孔二氧化硅纳米颗粒. 通过表面活性剂头部与带相反电荷的CSDAs之间的静电相互作用使氨基和羧基基团均匀排列在介孔孔道表面. 通过调节助溶剂或分散剂的加入量来控制颗粒粒径,调节合成溶液pH改变纳米颗粒表面羧基和氨基基团的电荷切换性及其量来控制颗粒的分散性.     

混合超分子液晶模板法合成六方介孔相含钛氧化硅

采用混合十六烷基三甲基溴化铵（CTAB）与不同碳链的脂肪胺（CnNH2n＋3, n=8,10,12,14,16）作模板,在四甲基氢氧化胺为碱源的条件下,合成了具有六方介孔结构的含钛氧化硅Ti MCM 41分子筛材料. XRD和TEM测试表明所合成材料具有高度的长程有序结构,样品的N2吸附/脱附等温线表明,高度有序的Ti MCM 41材料展示了毛细凝聚的陡峭台阶和狭窄的介孔孔径分布.对反应物配比中Ti/Si比、脂肪胺碳链长度n对六方介孔相结构的影响进行了研究,实验发现当Ti/Si< 0.15和n< 16时,均可获得具有六方介孔结构的含钛氧化硅Ti MCM 41;而当Ti/Si≥0.15或n >16时,产物将分别发生从六方向无定形态或从六方向层状介孔相结构的转移,从混合表面活性剂的堆积参数对这种相转移现象进行了分析.     

苯及苯磺酸基官能化的中孔分子筛的合成及催化应用

近年来 ,通过对介孔分子筛 (如 MCM,HMS,MSU-X)结构及组成的化学“裁剪”,制备具有特定结构和表面性质的催化材料成为该领域的研究热点之一 [1～ 5] .许多文献报道了 MCM-4 1的有机官能化中孔材料的制备技术 [5～ 8] ,并将其应用于有机合成反应 ,取得了较好的结果 [7,8] .其中 MSU-X介孔分子筛结构具有三维排列“Worm-like”孔道特征 ,有利于物料传输 ;相对于 MCM-4 1分子筛在合成方面具有以中性表面活性剂作模板剂且模板剂容易去除等诸多优点[9] .本文采用非离子表面活性剂 C11— 15H2 3— 31(CH2 CH2 O) 9H(AEO9)为模板剂 ,…     

高温水热合成具有高稳定性的有序介孔材料

高温水热合成路线作为合成具有超高稳定性的介孔材料越来越受到人们的重视.本文对高温水热合成有序介孔材料的发展过程作一个简单的综述,合成路线包括使用碳氟表面活性剂和碳氢表面活性剂作为复合模板,有机季铵盐与碳氢表面活性剂作为复合模板以及最近报道的采用碳氢表面活性剂作为单一模板来合成系列的有序介孔材料,其组成为二氧化硅、氧化钛硅以及聚合物等.     

Nonideal mixed micelles of Gemini surfactant homologues and their application as templates for mesoporous material MCM-48

The micellization properties of aqueous solutions of the mixed Gemini surfactant homologues GEM16-6-16 and GEM16-12-16 with various compositions were investigated. The measured critical micelle concentration (CMC) deviated significantly from the ideal mixing model. Good agreement was found with a nonideal mixing model, the Margules model, which has two optimal parameters, A12=-3.611 and A21=-6.318. It was shown that the properties of mixed micelles were not sensitive to the compositions, and most of the GEM16-12-16 molecules were aggregated into the micelles. Dynamic laser light-scattering measurements revealed that the mixed micelles had almost the same size and similar zeta potential. When the mixed micelles were used as templates, a series of highly ordered cubic MCM-48 mesoporous materials, characterized by XRD and TEM, were produced through self-assembly. The N2 adsorption-desorption measurements suggested that the pores of these materials had similar average diameters of 2.2-2.5 nm. This further demonstrated the nonideal behavior of the homologue mixture.     

Thermal Methods in the Synthesis of New Ordered Mesoporous Adsorbents

The synthesis of new ordered mesoporous adsorbents, specifically of the MCM-41 type, involves a step of thermal elimination of the template (a surfactant) where CRTA is shown to provide a 'soft chemistry' route. Once the mesoporous (i.e. 2 to 50 nm pore width) material is obtained, the pore size is determined by thermoporometry, a convenient application for low temperature DSC. Finally, the hydrophobic - hydrophilic properties of the pore walls are explored by immersion microcalorimetry in water. This revised version was published online in July 2006 with corrections to the Cover Date.     

Gemini surfactants at the air/water interface: a fully atomistic molecular dynamics study

Gemini surfactants typically consist of two single-chain surfactants chemically linked by a spacer molecule. We report herein the results of fully atomistic molecular dynamics (MD) simulations of a series of Gemini surfactants: CsH2s-alpha,omega-bis(C12H25N+(CH3)2Cl-), at the air/water interface with s = 3, 4, 6, 12, 14, and 16, at values of the initial surface area per surfactant AS = 70 A2, 77 A2, 95 A2, 151 A2, 133 A2, and 103 A2, respectively. The AS values employed were obtained from surface tension and neutron reflection experiments at the respective cmc of each surfactant. The Gemini surfactant corresponding to s = 3 was also simulated at AS = 105 A2, which is the experimentally derived value of surface area per surfactant at 1/10th of cmc. Only the surfactants with s = 12 and 14 and the surfactant with s = 3 at AS = 105 A2 gave a stable monolayer at the air/water interface. In other cases, we observe movement of some surfactant molecules from the air/water interface into the aqueous phase, resulting in a stable primary monolayer of surfactants at the air/water interface and a small concentration of surfactant molecules below it. The latter form aggregates, with their hydrophobic chains in the core. The density profiles along the normal to the interface are compared with the ones obtained from neutron reflection experiments. The MD simulations confirm the bending of the spacer toward the hydrophobic chains as the spacer length is increased and the spacer becomes more hydrophobic. The simulations have helped to shed light on the low-resolution picture which emerges from experimental analyses.     

Surfactant mediated control of pore size and morphology for molecularly ordered ethylene-bridged periodic mesoporous organosilica

A series of ethylene-containing mesoporous organosilica materials were fabricated via surfactant-mediated assembly of 1,2-bis(triethoxysilyl)ethylene (BTEE) organosilica precursor using alkyltrimethylammonium bromide (CnTAB) surfactants with different alkyl chain length (n=12, 14, 16, 18) as supramolecular templates. The presence of molecularly ordered ethylene groups in the resulting periodic mesoporous organosilica (PMO) materials was confirmed by XRD data along with 29Si and 13C MAS NMR analysis. Additional characterization techniques, namely nitrogen sorption, TEM, and TGA, confirmed the structural ordering and thermal stability of the molecularly ordered ethylene-bridged PMOs. The PMOs exhibit molecular-scale ordering (with a periodicity of 5.6 A) within the organosilica framework and tunable pore size, which depending on the alkyl chain length of the surfactant templates, varied in the range 23-41 A. Furthermore, depending on the alkyl chain length of the templates, the particle morphology of the PMOs gradually changed from monodisperse spheres (for C12TAB) to rod or cakelike particles (for C14TAB) and elongated ropelike particles for longer chain surfactants. Variations in the surfactant chain length therefore allowed control of both the pore size and particle morphology without compromising molecular-scale or structural ordering. The reactivity of ethylene groups was probed by bromination, which demonstrated the potential for further functionalization of the PMOs.     

Sol–gel encapsulation of bromothymol blue pH indicator in presence of Gemini 12-2-12 surfactant

A sol–gel approach was used to encapsulate bromothymol blue (BTB) C₂₇H₂₈Br₂O₅S pH indicator into mesoporous silica material, in presence of ethanediyl-1,2-bis(dimethyldodecylammonium chloride) (Gemini 12-2-12) surfactant. An ordered mesoporous inorganic matrix including Gemini 12-2-12 and BTB was obtained. It is found that encapsulated BTB/Gemini 12-2-12 exhibit same behavior for pH change as that of the free BTB, which indicate that only physical interaction between BTB molecules and host mesoporous silica network are obtained. The addition of Gemini 12-2-12 surfactant has increased the porosity of the host silica material and increased its sensing capability. The presence of Gemini 12-2-12 surfactant has shifted pKa values of the system to more acidic in comparison with that of free BTB, BTB entrapped silica and BTB/CTAB entrapped silica.     

One pot synthesis of ordered mesoporous organosilica particles bearing propyl-, octyl- and hexadecyl-chains

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.     

含有酰胺基或酯基的可降解阳离子Gemini表面活性剂在水溶液中的聚集行为

In the last thirty years, Gemini surfactants with various structures have been designed, synthesized, and demonstrated to show superior physicochemical properties. However, the utilization of non-degradable surfactants, including these Gemini surfactants, poses a threat to the environment; hence, degradable Gemini surfactants are desirable. Herein, biodegradable cationic Gemini surfactants with amide or ester groups in the hydrophobic chains or the spacer were synthesized. A monomeric surfactant containing an amide group and a Gemini surfactant with amide groups both in the hydrophobic chains and the spacer were synthesized for comparison. The effects of amide group location on the aggregation behavior of Gemini surfactants were studied systematically. The differences between the Gemini surfactants with amide groups and Gemini surfactants with ester groups were evaluated by comparing their aggregation behavior and hydrogen bonding formation. The Gemini surfactants with amide groups (C₁₂A-C_n-AC₁₂) in the chains showed much larger exothermic ΔH_mic and more negative ΔG_mic values than those of the corresponding monomeric surfactant C₁₂A; besides, their critical micelle concentration (cmc) was more than one order of magnitude lower than that of C₁₂A. The amide groups located in the hydrophobic alkyl chains promoted hydrogen bonding formation and self-assembly of the Gemini surfactants C₁₂A-C_n-AC₁₂. Moreover, ¹H NMR spectra revealed that the co-effect of a short spacer and hydrogen bonding leads to slow exchange of the C₁₂A-C₂-AC₁₂ molecules between the monomer and the aggregate. For the Gemini surfactant series C₁₂-AC_nA-C₁₂, the amide groups notably increased the spacer length, and largest cmc value and smallest exothermic ΔH_mic value were observed for C₁₂-AC₂A-C₁₂ instead of C₁₂-AC₆A-C₁₂. In C₁₂-AC₁₂A-C₁₂, the spacer was long and sufficiently flexible to adopt a "U"-shaped conformation above the cmc, and it acted as the hydrophobic part of the surfactant, as confirmed by ¹H NMR spectra. Among the Gemini surfactant with amide groups in both the spacer and the hydrophobic alkyl chains, C₁₂A-AC₆A-AC₁₂ had a smaller cmc and I₁/I₃ ratio as well as more exothermic ΔH_mic values than those of C₁₂A-C₆-AC₁₂ and C₁₂-AC₆A-C₁₂. ¹H NMR spectra indicated that an ester-alcohol structural equilibrium exists during aggregation for the Gemini surfactants with ester groups. In addition, the Gemini surfactants with ester groups formed water-mediated hydrogen bonds in the aggregates. This water-mediated hydrogen bonding between ester groups was weaker than the direct hydrogen bonding between amide groups. Therefore, the Gemini surfactants with ester groups, C₁₂E-C₆-EC₁₂ and C₁₂-EC₆E-C₁₂, exhibited lower surface activity, a larger micelle ionization degree, higher micropolarity, and smaller exothermic ΔH_mic and less negative ΔG_mic values than their counterparts with amide groups, C₁₂A-C₆-AC₁₂ and C₁₂-AC₆A-C₁₂.     

Novel route to periodic mesoporous aminosilicas, PMAs: ammonolysis of periodic mesoporous organosilicas

A new route to periodic mesoporous aminosilicas (PMAs) that contain amine functional groups in the framework of a mesoporous network is reported. The materials are prepared via thermal ammonolysis of periodic mesoporous organosilicas (PMOs) under a flow of ammonia gas. PMOs integrate similar or even higher quantities of nitrogen-containing groups upon ammonolysis than similarly treated ordered mesoporous silicas (MCM-41). The quantity of amine groups introduced into the materials was found to depend strongly on the ammonolysis temperature. The largest loading of amine groups was obtained when a well-ordered cubic methylene PMO material without prior vacuum-drying was thermolyzed in ammonia. The ordered mesoporosity of PMOs was preserved during the ammonolysis with only a slight decrease in the mesopore size and the degree of mesostructural ordering. The extent of substitution of framework oxygen by amine and nitride groups was established by solid-state (29)Si CP-MAS, (29)Si MAS, (15)N MAS, and (13)C CP-MAS NMR spectroscopies, elemental analysis, and X-ray photoelectron spectroscopy. In some cases, methylene and methyl functional groups were also present in the PMAs along with amine functional groups, as inferred from elemental analysis and gas adsorption, particularly in cases where PMOs were subjected to ammonolysis at 400 and 550 degrees C for several hours. This resulted in new multifunctional mesoporous organoaminosilica nanomaterials with properties that could be tuned by systematically varying the relative amounts of hydrophilic amine and hydrophobic hydrocarbon pendent and framework groups. The stability upon storage was found to be much higher for PMAs obtained from PMOs than for those obtained from MCM-41 silicas under the same conditions.     

Surfactant effects on the physical properties of mesoporous silica and silicates

Mesostructured silicas and silicates have been synthesized using hydrogels with molar composition: M:26.0SiO₂:5.2(C₂H₅)₄NOH:7.5[CH₃(CH₂)₁₅N(CH₃)₃]₂O:790H₂O, where M=0, Zr(OC₃H₇)₄ or Ti(OC₄H₉)₄. In all preparations, colloidal silica (Ludox) was used as the source of silica. The hydrothermal transformation at 110°C of these gels produced solids with the hexagonal structure typical of MCM-41 type materials. The effects of chain length and surfactant terminal alkyl groups on the properties of mesoporous materials containing Ti or Zr, have been investigated by using different surfactants such as cetyl trimethyl ammonium bromide and chloride, cetyl dimethyl ethyl ammonium bromide, and myristyl trimethyl ammonium bromide. When the surfactant's carbonyl chain decreased to 14 from 16 carbon atoms, a reduction in unit cell dimension and average pore diameter was observed in the mesoporous silicas, titaniumsilicates and zirconiumsilicates under study. Replacement of methyl groups with ethyl groups on the surfactant hydrophobic head, had no measurable effects on crystals' properties. However, a surfactant with a bulky aromatic head group, such as cetyl pyridinium chloride, inhibited crystallization. In general, the use of bromide in place of chloride salts yielded more ordered MCM-41 type crystals. The high thermal stability (to 800°C), surface area (1000–1500 m²/g), pore volume (0.90–1.20 cm³/g) and uniform mesoporosity (with pore diameter in the 2.9 nm–3.6 nm range), of these metalsilicates could be of particular interest in the preparation of catalysts requiring siliceous metal supports.