Synthesis and characterization of SBA-3, SBA-15, and SBA-1 nanostructured catalytic materials

A highly ordered large pore mesoporous silica molecular sieve SBA-3, SBA-15, Al-SBA-15, and SBA-1, were developed and characterized by XRD, BET, FTIR, SEM, and NMR-MAS. The catalytic materials were synthesized using different raw materials and operation conditions. These materials contain a regular arrangement of uniform channels with diameters between 1.8 and 10 nm, high specific surface area and high specific pore volume. The designed methods were effective for the synthesis, presenting each mesostructured materials, patterns of XRD and other characteristics corresponding to the reported ones in literature. The new route employed to synthesize Al-SBA-15, generates a catalyst with only aluminum in tetrahedral form, according to the data of (27)Al NMR-MAS. However, several reports indicated that the coordination of the Al atoms changes below the Si/Al ratio of 45, presenting peaks corresponding to penta and hexa-coordinated aluminum, which are absent in our samples (Si/Al = 50 and 33).     

One-step direct synthesis of mesoporous aluminosilicates Al-SBA-15 with cage-like macropores by using micrometer-sized aluminum balls

Ordered mesoporous aluminosilicate Al-SBA-15 materials with cage-like macropores have been synthesized by using micrometer-sized aluminum balls as an Al source, tetraethyl orthosilicate (TEOS) as a silica source, and triblock copolymer Pluronic P123 as a template. The resulting materials were fully characterized by XRD, N₂ adsorption, SEM, TEM, ICP-AES, and ²⁷Al MAS-NMR. The products (Al-SBA-15) have ordered two-dimensional (2-D) hexagonal mesostructures (space group p6mm). The calcined Al-SBA-15 materials exhibit disordered macropores with diameters of about 70–80 nm and ordered mesopores with a diameter of ∼5 nm, a BET surface area of about 500 m²/g, Si/Al ratio of 40–80, and a ratio of tetrahedral Al to octahedral Al sites of about 2:1. This combination of properties gives these materials potential applications in areas such as adsorption, catalysis and separation. Supported by the National Natural Science Foundation of China (Grant Nos. 20890123 & 20721063), Shanghai Science & Technology Committee (08DZ2270500), and Shanghai Leading Academic Discipline Project (No.B108)     

Effect of the concentration of aluminum on the adsorption,texture, and structure characteristics of a mesoporous mineral mesophase of the SBA-15 type

The effect of Al ion implantation on the properties of mesoporous aluminosilicate mineral phases of the SBA-15 type was studied. The implantation of Al was performed immediately under conditions of the synthesis of SBA-15 in a weakly acidic medium (pH ～ 2.9). It was found that, under these conditions, the amount of Al that can be implanted into the SBA-15 framework is limited (a maximum of 7.2 mol %). According to XPS data, aluminum ions were implanted into the matrix of silica rather than occurring on the surface as an individual phase. The study of nitrogen adsorption at 77 K and the results obtained by X-ray diffractometry and high-resolution electron microscopy suggest that Al-SBA-15 materials exhibited a hexagonal structure of channel pores of the same diameter of 8.3 nm, and the unit cell parameter was 12.3 nm. The degree of crystallinity of the material increased with the concentration of Al.     

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。     

一步由微米铝球直接合成含笼状大孔的Al-SBA-15

以微米铝球为铝源,正硅酸乙酯(TEOS)为硅源,聚醚三嵌段聚合物P123为模板剂,在酸性水溶液中,一步直接合成含有笼状大孔的介孔氧化硅(铝)分子筛Al-SBA-15.用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、27Al固体核磁(27AlMAS-NMR)、ICP发射光谱仪、X射线衍射(XRD),以及低温N2吸/脱附对样品进行了表征.结果表明,得到的材料是二维六方结构(空间群p6mm)的Al-SBA-15,经过550℃焙烧后,Al-SBA-15的比表面积大约为500m2/g,Si/Al比在40～80之间,四配位铝/六配位铝之比约为2,结构中存在约70～80nm的笼型大孔和约为5nm的介孔.     

Characterization and acidic properties of Al-SBA-15 materials prepared by post-synthesis alumination of a low-cost ordered mesoporous silica

A series of Al-containing SBA-15 type materials with different Si/Al ratio, were prepared by post-synthesis modification of a pure highly ordered mesoporous silica SBA-15 obtained by using sodium silicate as silica source, and amphiphilic block copolymer as structure-directing agent. A high level of aluminum incorporation was achieved, reaching an Si/Al ratio of up to 5.5, without any significant loss in the textural properties of SBA-15. These materials were fully characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ²⁷Al NMR spectroscopy, and N₂ adsorption at 77 K. The acid properties of these materials have been evaluated by NH₃-TPD, adsorption of pyridine and deuterated acetonitrile coupled to FTIR spectroscopy. The effective acidity of these materials was evaluated using two catalytic reactions: 2-propanol dehydrogenation and 1-butene isomerization. The adsorption of basic probe molecules and the catalytic behavior revealed an evolution of the acid properties with the Al content. These studies have shown that the Al-SBA-15 materials contain Brønsted and Lewis acid sites with medium acidity which makes them appropriate to be used as acid catalysts in heterogeneous catalysis, catalytic supports, and adsorbents.     

具有双孔径分布的介孔C-Al2O3-TiO2纳米复合材料的合成及其红外发射率

以嵌段共聚物F127 (PEO₁₀₆PPO₇₀PEO₁₀₆, M_W=12600)为模板剂, 异丙醇铝和钛酸四丁酯为金属源, 低分子量的酚醛树脂为碳源, 通过溶胶-凝胶三元共组装法合成了具有双孔径分布的C-Al₂O₃-TiO₂纳米复合材料.用X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)及N₂吸附-脱附对该复合材料进行结构表征. 结果显示, 当铝钛原子的摩尔比为1:10 时, 对应的纳米复合材料具有较好的有序介孔结构, 其双孔径分别为3.9和6.5 nm, 比表面积可达259 m²·g^-1, 孔容0.37 cm³·g^-1. 以三元乙丙橡胶(EPDM)为粘结剂, 与介孔纳米复合材料混合制备涂层. 通过调节复合材料中铝钛摩尔比和涂层厚度, 红外发射率在0.450-0.617之间可调.     

有序介孔C-Al2O3纳米复合材料的合成及其红外发射率

以嵌段共聚物F127(PEO106PPO70PEO106, MW=12600)为模板剂, 异丙醇铝为铝源, 低分子量的酚醛树脂为碳源, 通过溶胶-凝胶三元共组装法合成了C-Al2O3纳米复合材料. 用X射线衍射(XRD)、透射电子显微镜(TEM)及N2吸脱附法对该复合材料进行结构与性能表征, 结果显示复合材料MC5A5具有较好的有序介孔结构, 其比表面积可达175 m2·g-1, 孔容0.22 cm3·g-1. 又以三元乙丙橡胶(EPDM)为粘结剂, 与介孔纳米复合材料混合制备涂层. 随着复合材料中Al2O3质量分数从30%增加到70%, 该涂层的红外发射率从0.575降至0.456, 表明Al2O3能有效降低复合材料的红外发射率, 预示该复合材料在军事装备隐身需求领域将具有较好的应用前景.     

The Metal–Organic Framework MIL‐53(Al) Constructed from Multiple Metal Sources: Alumina,Aluminum Hydroxide,and Boehmite

Three aluminum compounds, namely alumina, aluminum hydroxide, and boehmite, are probed as the metal sources for the hydrothermal synthesis of a typical metal–organic framework MIL‐53(Al). The process exhibits enhanced synthetic efficiency without the generation of strongly acidic byproducts. The time‐course monitoring of conversion from different aluminum sources into MIL‐53(Al) is achieved by multiple characterization that reveals a similar but differentiated crystallinity, porosity, and morphology relative to typical MIL‐53(Al) prepared from water‐soluble aluminum salts. Moreover, the prepared MIL‐53(Al) constructed with the three insoluble aluminum sources exhibit an improved thermal stability of up to nearly 600 °C and enhanced yields. Alumina and boehmite are more preferable than aluminum hydroxide in terms of product porosity, yield, and reaction time. The adsorption performances of a typical environmental endocrine disruptor, dimethyl phthalate, on the prepared MIL‐53(Al) samples are also investigated. The improved structural stability of MIL‐53(Al) prepared from these alternative aluminum sources enables double‐enhanced adsorption performance (up to 206 mg g^?1) relative to the conventionally obtained MIL‐53(Al).     

MnOx/Al-SBA-15的结构性质及低温NH3选择性催化还原NOx

采用后合成法制备MnO_x/Al-SBA-15催化剂, 考察了催化剂的低温NH₃选择性催化还原(SCR)NO_x的性能. 利用傅里叶透射红外变换(FTIR)光谱、N₂吸附-脱附、X射线衍射(XRD)、扫描电镜(SEM)、拉曼光谱(Raman)、X射线光电子能谱(XPS)及NH₃程序升温脱附(NH₃-TPD)的表征手段, 对催化剂的结构性质和SCR性能进行了系统分析. 结果表明, 适量Al的掺杂能提高MnO_x/SBA-15催化剂的SCR活性, 当硅铝摩尔比为50时, 催化剂活性最佳. 表征结果显示, Al掺杂后, 催化剂仍保持良好的骨架结构, 较大比表面、孔容和孔径, 并且Mn在催化剂表面富集, 由低价态转化为高价态, MnO₂为催化剂的主要活性相. 此外, Al的掺杂使MnO_x在催化剂表面高度分散, 表面酸性增强, 从而提高了催化剂的SCR活性.     

Synthesis and characterization of highly ordered mesoporous nanomaterials Al-MCM-41 and Al-SBA-15 from bentonite as efficient catalysts for the production of biodiesel MELA and EELA

Research on Chemical Intermediates - Low-cost Al-MCM-41 and Al-SBA-15 mesoporous materials are successfully synthesized from bentonite as silicon and aluminum sources instead of laboratory reagents...     

Template-directed synthesis of ordered single-crystalline nanowires arrays of Cu2ZnSnS4 and Cu2ZnSnSe4

Highly ordered quaternary semiconductor Cu(2)ZnSnS(4) nanowires array have been prepared via a facile solvothermal approach using anodic aluminum oxide (AAO) as a hard template. The as-prepared nanowires are uniform and single crystalline. They grow along either the crystalline [110] or [111] direction. The structure, morphology, composition, and optical absorption properties of the as-prepared Cu(2)ZnSnS(4) samples were characterized using X-ray powder diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning electron microscopy, and UV-vis spectrometry. A possible formation mechanism of the nanowire arrays is proposed. Governed by similar mechanism, we show that Cu(2)ZnSnSe(4) nanowire array with similar structural characteristics can also be obtained.     

AlMCM-41介孔分子筛的合成及表征

以拟薄水铝石为铝源、水玻璃为硅源、十六烷基三甲基溴化铵为模板剂,在110℃时水热晶化合成了含Al的MCM-41介孔分子筛.采用X射线衍射(XRD)、N2吸附-脱附、固体29Si、27Al魔角旋转核磁共振技术(MASNMR)、扫描电镜(SEM)及吡啶吸附傅里叶变换红外(FTIR)光谱技术对AlMCM-41分子筛进行了表征.结果表明:AlMCM-41分子筛具有六方排列的孔道结构,同时具有很高的相对结晶度、比表面积和孔容,且孔分布单一;AlMCM-41分子筛中Si原子在骨架内键合的程度更高,使AlMCM-41分子筛具有更好的骨架晶化程度;同时具有四配位骨架铝,使AlMCM-41介孔分子筛具有适当的酸性.     

镁热还原法制备有序介孔Si/C锂离子电池负极材料及其电化学性能

以SBA-15为前驱体,在660 ℃下通过镁热还原反应得到介孔硅材料,并对其进行碳包覆处理,成功地制备了有序介孔Si/C（OMP-Si/C）复合材料。该OMP-Si/C材料保留了SBA-15模板的有序蜂窝孔道,并且形成具有高堆积密度的莲藕链束结构。文中还提出了一个SBA-15镁热还原液态环境反应模型,探讨了660 ℃下硅的高度有序介孔与莲藕链束结构的形成机理。利用X射线衍射（XRD）仪、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、氮气吸脱附法及拉曼光谱对样品物相和微观形貌进行了表征。这种高度有序介孔Si/C复合材料具有优异的电化学性能,展现出其在第二代锂电池负极材料领域中的潜在应用价值。     

Iron-functionalized Al-SBA-15 for benzene hydroxylation

For the first time an ordered mesoporous silica (Fe-Al-SBA-15) with catalytically active isolated Fe surface species for the hydroxylation of benzene with nitrous oxide is prepared by introduction of Fe3+ in the synthesis gel of Al-SBA-15.     

Preparations of polystyrene/aluminum hydroxide and polystyrene/alumina composite particles in an ionic liquid

Polystyrene (PS)/aluminum hydroxide (Al(OH)(3)) composite particles were successfully prepared by the sol-gel process of aluminum isopropoxide (Al(OPr(i))(3)) in a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]) using ammonium hydroxide (NH(4)OH) as a catalyst in the presence of PS seed. Transmission electron microscopy observation of ultrathin cross-sections of the composite particles revealed that the composite particles had a core-shell morphology consisting of a PS core and a Al(OH)(3) shell having high crystallinity. The amount of secondary nucleated Al(OH)(3) could be reduced by dropwise addition of NH(4)OH. Moreover, PS/η-Al(2)O(3) composite particles were successfully prepared by heat treatment of PS/Al(OH)(3) at 300 °C in N(2) atmosphere, which is below the decomposition temperature of PS.     

LY12铝合金表面电化学沉积制备DTMS硅烷膜及其耐蚀性研究

采用电化学技术在LY12铝合金表面沉积制备了十二烷基三甲氧基硅烷(DTMS)膜. 反射吸收红外光谱表明, DTMS硅烷试剂与铝合金基体表面发生了化学键合作用, 生成—SiOAl键实现成膜. 通过对膜覆盖电极在质量分数为3.5%的NaCl溶液中的电化学阻抗谱(EIS)测试结果表明, 与开路电位下相比, 采用阴极电位沉积方法得到硅烷膜的耐蚀性能有明显提高, 且存在一个最佳“临界电位”, 在此电位下沉积得到的硅烷膜具有最高的耐蚀性. 扫描电镜观察结果表明, 在“临界电位”下制备得到的硅烷膜的结构最致密. 给出了硅烷膜覆盖电极的阻抗模型及相关参数的拟合结果.     

Encapsulation of aluminum flakes with hybrid silica/poly(acrylic acid) nanolayers by combination of sol–gel and in situ polymerization methods: a corrosion behavior study

A combination of sol–gel method and in situ polymerization was used to form a hybrid silica/poly(acrylic acid) nanolayer for the corrosion protection of aluminum pigments. To this end, the pigment particles were first coated with a silica layer by sol–gel method. Tetraethylorthosilicate was used as a precursor and during a condensation reaction, an inorganic silica layer was formed. Then, 3-methacryloxypropyltrimethoxysilane was attached on the surface and in situ polymerization of acrylic acid (AA), as a hydrophile monomer, was performed. The obtained Al/Si/PAA flakes were characterized by different methods such as Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy (TEM). The attached PAA chains on the surface were deattached by HF aqueous solution and analyzed by gel permeation chromatography. Also, the surface energy of samples was measured using Owens and Wendt equation by means of contact angle data. As results, the characterizing tests approved the successful encapsulation of Al pigments and TEM image showed a 10–15 nm silica layer and a 20–25 nm PAA layer. Although the Al/Si pigments showed a quantity of evolved hydrogen, the hybrid coated pigments had excellent anticorrosive properties in acidic and alkaline solutions. Also, the surface free energy of Al/Si/PAA showed an increase compared to that of Al.     

High catalytic activity for CO oxidation of gold nanoparticles confined in acidic support Al-SBA-15 at low temperatures

While there is a large number of recent studies of Au nanocatalysts supported on metal oxides, low-temperature CO oxidation under an acidic environment has not yet been accomplished. Over a novel acidic Al-SBA-15 support, uniformly distributed gold nanoparticles with sizes approximately 2.7 nm were obtained by a successive procedure of aminosilane grafting, gold adsorption-reduction, and then high-temperature hydrogen treatment. The catalyst system, Au@Al-SBA-15, exhibits extraordinarily high activity for CO oxidation at 80 degrees C. By varying the Si/Al ratio of the support, the dependence of the catalytic activity on the support Si/Al ratio was found in the CO oxidation reaction.     

氨基功能化短孔道有序介孔材料H_2N-Zr-Ce-SBA-15的合成及吸附性能

以pluronic(P123)为模板剂,正硅酸乙酯(TEOS)为硅源,氯化氧锆和硝酸亚铈为无机前驱盐,N-(2-氨乙基)-3-氨丙基三甲氧基硅烷(AAPTS)为硅烷化试剂,采用后接枝法合成了氨基功能化六方板状短孔道有序介孔材料H2N-Zr-Ce-SBA-15(H2N-ZCS).采用小角X射线衍射(LXRD)、傅里叶变换红外(FTIR)光谱、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、热重分析、N2吸附/脱附等手段对H2N-ZCS进行了表征.结果表明AAPTS成功地嫁接到有序介孔材料上,H2N-ZCS仍保持了类似于传统SBA-15高度有序的二维六方相介孔结构,且孔道方向垂直于该六方板面.对阴离子染料酸性品红吸附实验表明,H2N-ZCS比H2N-SBA-15具有较强的吸附能力.这种功能化短孔道、大径轴比的六方板状介孔材料在吸附、分离及催化等领域中能更有效地促进分子的扩散传递.