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。     

FTIR spectroscopic study of titanium-containing mesoporous silicate materials

The surface acidity of different mesoporous titanium-silicates, such as well-organized hexagonally packed Ti-MMM, Ti-MMM-2, Ti-SBA-15, and amorphous TiO(2)-SiO(2) mixed oxides (aerogels and xerogels), was studied by means of FTIR spectroscopy of CO adsorbed at 80 K and CD(3)CN adsorbed at 293 K. The surface hydroxyl groups of mesoporous titanium-silicates with 2-7 wt % Ti revealed a Br?nsted acidity slightly higher to that of pure silicate. TiO(2)-SiO(2) xerogels revealed the highest Br?nsted acidity among the titanium-silicates studied. CO adsorption revealed two additional sites on the surface in comparison to pure silicate, characterized by nu(CO) from 2185 (high pressure) to 2178 (low pressure) cm(-1) and from 2174 (high pressure) to 2170 (low pressure) cm(-1). These bands are due to CO adsorbed on isolated titanium cations in the silica surrounding or having one Ti(4+) cation in their second coordination sphere and due to CO interactions with Ti-OH groups, respectively. CD(3)CN adsorption similarly revealed the existence of two additional sites, which were not detected for pure silicate: at 2289 cm(-1) due to CD(3)CN interaction with titanol groups and from 2306 (low pressure) to 2300 (high pressure) cm(-1) due to acetonitrile interaction with isolated framework titanium cations with probably one Ti(4+) cation in their second coordination shell. The spectroscopic results are compared with computational data obtained on cluster models of titanium-silicate with different titanium content. According to the IR data, the Ti accessibility on the surfaces for mesoporous titanium-silicates with similar Ti loading (2 wt %) was found to fall in the order TiO(2)-SiO(2) aerogel approximately TiO(2)-SiO(2) xerogel > Ti-MMM approximately Ti-MMM-2 > Ti-SBA-15. This order (except TiO(2)-SiO(2) xerogel) correlates with the catalytic activity found previously for titanium-silicates in 2,3,6-trimethylphenol oxidation with H(2)O(2).     

硅胶负载氯掺杂二氧化钛光催化剂的水热制备与光催化活性评价

利用水热法, 以硅胶为载体, 以Ti(SO4)2为钛源, NaCl为氯源制备了具有良好性能的硅胶负载氯掺杂二氧化钛(CTS)光催化剂, 考察了氯投加量、焙烧温度及钛硅比对光催化活性的影响. 结果表明, 氯投加量为15% (nCl/nTi)、钛硅物质的量比为3:1、焙烧温度为750 ℃时制备的CTS具有最佳的光催化活性, 其比表面积为60.8 m2·g-1. CTS中的硅胶除了作为载体, 还起到了促进锐钛矿二氧化钛的生成并抑制其向金红石相转变的作用; 氯掺杂二氧化钛(CT)经硅胶负载后, 其表面孔结构发生了变化, 并且热稳定性增加. 苯酚降解实验表明, 与CT相比, CTS以0.7740 g·g-1的二氧化钛含量具有更高的光催化活性.     

Ti-SBA-15介孔材料用于磷酸化肽的高效富集

结合基质辅助激光解吸飞行时间质谱(MALDI-TOF MS)检测技术,考察了Ti-SBA-15介孔材料对β-酪蛋白酶解产物中磷酸化肽的选择性富集性能。实验结果显示,含Ti和Si物质的量比为0.08的Ti-SBA-15介孔材料可选择性地对β-酪蛋白酶解产物中的磷酸化肽进行选择性富集;对于β-酪蛋白和牛血清白蛋白物质的量比为1:100的蛋白质酶解混合液,Ti-SBA-15仍能实现对其磷酸化肽的有效富集。上述结果表明,作为一种多孔、高比表面积的磷酸化多肽的选择性吸附材料,Ti-SBA-15有望在磷酸化蛋白质组的分析中得到广泛的应用。     

Comparative study of niobium-containing hexagonal mesoporous silicas prepared using different niobium sources

Two groups of niobium-containing hexagonal mesoporous silica (Nb-HMS) samples were prepared hydrothermally using niobium oxalate and niobium ethoxide as Nb source, respectively. The samples were characterized by XRD, N₂-adsorption, ICP-AES, UV-Vis, respectively. They were also evaluated by the epoxidation of cyclohexene with cumene hydroperoxide (CHP) as oxidant. It is revealed that the samples possess typical hexagonal mesoporous structure in which most of Nb species exist in the form of framework pentahedral coordinated state. Meanwhile, the Nb-HMS samples from niobium ethoxide give more excellent catalytic performance than those from niobium oxalate. It is likely because that the former samples have a higher total amount of Nb species and a higher proportion of isolated framework Nb species. Accordingly, niobium ethoxide is a better niobium source than niobium oxalate.     

Effect of titanium source on structural properties and acidity of Ti-pillared bentonite

Ti-pillared bentonites (Ti-PBs) were synthesised using bentonite from the Hanç?l? region in Turkey. Ti(IV) chloride, Ti(IV) ethoxide and Ti(IV) propoxide were used as the titanium sources; the syntheses were carried out using different H⁺/Ti ratios, bentonite suspension percentages and calcination temperatures. Titanium was found in the form of titanium dioxide for all the sources. The Ti(IV) chloride source afforded a sample with a significantly higher specific BET surface area (by 323 m² g^?1), TiO₂ content of 50.5 mass % and a more microporous structure with a micropore volume of 0.112 cm³ g^?1; the Ti(IV) propoxide source afforded a more mesoporous structure with a higher total pore volume. The micropore region showed the formation of pores of different sizes, while prominent narrow peaks were obtained in the mesopore region. Ti-PBs, which exhibited only the anatase phase of titanium dioxide, yielded high Brønsted and Lewis acidities. When the rutile phase and the anatase phase occurred together, as a result of the lower TiO₂ content, the Brønsted and Lewis acidities of the Ti-PBs decreased. The use of Ti(IV) chloride and Ti(IV) propoxide sources at H⁺/Ti ratios of 4.0 and a bentonite suspension percentage of 2.0 resulted in samples exhibiting strong Brønsted acidity.     

Comparative Study of Titanium-modified HMS Mesoporous Materials via Different Preparing Methods

The current work is focused on the testing of titanium modified hexagonal mesoporous silica (HMS) for catalysts in epoxidation of cyclohexene. Two samples were prepared via the chemical liquid deposition (CLD) and the chemical vapor deposition (CVD), namely Ti/HMS-L and Ti/HMS-V, respectively. HMS and Ti/HMS were characterized by XRD, N₂-adsorption, ICP-AES, UV-Vis. The samples were also evaluated by the epoxidation of cyclohexene with cumene hydroperoxide (CHP) as oxidant. It is revealed that Ti/HMS samples possess typical hexagonal mesoporous structure in which most of titanium species exist in the form of framework tetracoordinated state. Meanwhile, Ti/HMS-V is more seriously affected than Ti/HMS-L since the former was prepared at higher temperature. Ti/HMS-V gives more excellent catalytic performance than Ti/HMS-L, which is likely because the former has more isolated and framework titanium species. Either Ti/HMS-V or Ti/HMS-L can be used only 1 time in epoxidation experiment.     

Room temperature synthesis of Ti-SBA-15 from silatrane and titanium-glycolate and its catalytic performance towards styrene epoxidation

A novel room temperature sol–gel synthesis of Ti-SBA-15 is described using moisture stable silatrane and titanium glycolate precursors, and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer (EO₂₀PO₇₀EO₂₀) as the structure directing agent. Catalyst performance was optimized by systematically investigating the influence of acidity, reaction time and temperature, and titanium loading. Small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) showed well-ordered 2D mesoporous hexagonal structures, while N₂ adsorption/desorption measurements yielded high surface areas (up to 670 m²/g), with large pore diameters (5.79 nm) and volumes (0.83 cm³/g). Diffuse reflectance UV–visible spectroscopy (DRUV) was found that tetravalent titanium as Ti⁴⁺O₄ tetrahedra were incorporated in the framework through displacement of Si⁴⁺O₄ after calcination (550°C/6 h) to loadings of 7 mol% Ti without perturbation of the ordered mesoporous structure, or decoration by extra-framework anatase containing Ti⁴⁺O₆ octahedra. The catalytic activity and selectivity of styrene epoxidation using hydrogen peroxide (H₂O₂) showed that the conversion of styrene increases significantly at higher titanium contents. The only products of this reaction were styrene oxide and benzaldehyde, with selectivity of 34.2 and 65.8%, respectively, at a styrene conversion of 25.8% over the 7 mol% Ti-SBA-15 catalyst. Beyond this titanium loading, anatase is deposited on the framework and catalytic activity degrades. The performance of the new catalyst is also shown to be superior to conventional materials produced by incipient wetness impregnation where Ti resides on the surface of SBA-15, giving a styrene conversion of 11.9% under identical reaction conditions.     

含钛CDS-1分子筛的水热合成与表征

以钛酸正丁酯（TBOT）为钛源、以发烟硅胶为硅源、以四甲基氢氧化铵（TMAOH）为模板剂,采用了一步法直接水热合成了CDO晶体结构的含钛分子筛,Ti-CDS-1。用粉末X-射线衍射、电子扫描、紫外可见漫反射光谱,傅立叶变换红外光谱等手段对所合成的样品进行了表征,结果表明,Ti-CDS-1维持原来全硅分子筛的片状晶体外形;原料中钛原子大部分嵌入到CDS-1分子筛分子筛骨架,少量钛在分子筛表面形成八面体非骨架钛物种,这部分骨架外钛可以用酸处理选择性去除。     

Al-TS-1的合成及催化氧化性能

系统研究了Al掺杂TS-1(Al-TS-1)分子筛的合成及其催化氧化性能,采用X射线衍射、紫外-可见光谱、电感耦合等离子体发射光谱、扫描电镜、²⁷Al和²⁹Si固体核磁共振等手段对Al-TS-1样品进行了表征.结果表明,在合成过程中,Al的引入会影响TS-1中骨架Ti的形成,但当Al含量低于一定值(Al/Si≤0.005)时,其影响很小.Al-TS-1中骨架Al和骨架Ti均不对其相应的酸催化和催化氧化作用产生影响.骨架Al抑制了Al-TS-1在碱性应用体系中的与Ti相邻Si的溶脱,从而保护了骨架Ti活性中心.     

Highly ordered Ti-SBA-15: Efficient H2 adsorbent and photocatalyst for eco-toxic dye degradation

Highly ordered 2D-hexagonal mesoporous titanium silicate Ti-SBA-15 materials (space group p6mm) have been synthesized hydrothermally in acidic medium employing amphiphilic tri-block copolymer, Pluronic F127 as structure directing agent. Samples are characterized by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, FT IR spectroscopy, UV-visible diffuse reflectance measurements, N₂ adsorption/desorption and TG-DTA analysis. XRD and TEM results suggested the presence of highly ordered mesophase with hexagonal pore arrangements. BET surface area for Ti-SBA-15 (924 m² g⁻¹) is considerably higher than the pure silica SBA-15 (611 m² g⁻¹) prepared following the same synthetic route. UV-visible and FT-IR studies suggested the incorporation of mostly tetrahedral titanium (IV) species, along with some six-coordinated sites in the silicate network. This material shows very good H₂ adsorption capacity at higher pressure and excellent catalytic activity in the photocatalytic degradation of ecologically abundant dye methylene blue.     

Morphology and dispersion control of titania–silica monolith with macro–meso pore system

Macroporous gels with bicontinuous morphology in micrometer range were prepared in a titania?Csilica system containing 5 and 7.6 mass?% titania using tetraethoxysilane and four kinds of Ti precursors, two titanium alkoxides, titanium chloride and titanium sulfate, under coexistence of poly(ethylene glycol) (PEG) with an average molecular weight of 20,000. In all the systems with different Ti precursors, the addition of PEG induced phase separation, and the macroporous morphology was formed when the transitional structure of phase separation was frozen-in by sol?Cgel transition of inorganic components. However, we can see large differences in phase separation tendency and Ti dispersion in silica network depending on the Ti precursors used. When titanium alkoxides were added into pure silica sol?Cgel system, phase separation tendency largely decreased, so that low temperature reaction was necessary for macropore formation. When we used titanium salts, on the other hand, phase separation tendency does not change much from pure silica system. The difference has been tentatively attributed to the difference in the mixing level of Ti in silica network. Although titania tended to aggregate when titanium alkoxides were used as precursors, Ti could be well dispersed in silica gel matrix when acetylacetone was added in the alkoxide system or when titanium salts were used as Ti precursors.     

以硅溶胶和三氯化钛为原料合成Ti-MCM-41分子筛 Ⅰ. Ti-MCM-41分子筛的合成

 以硅溶胶和TiCl3水溶液为原料,采用水热合成方法制备了结晶度和长程有序性较高的中孔Ti－MCM－41分子筛．钛的加入提高了中孔分子筛的长程有序性．辅助模板剂的选择对分子筛的合成很重要,其中以四甲基氢氧化铵和四乙基氢氧化铵作辅助模板剂的效果较好．四甲基氢氧化铵的用量对分子筛的结晶度和长程有序性也有影响,用量过高和过低都会降低分子筛的结晶度．合成的分子筛中的钛含量（摩尔分数）可以达到3．75％,进一步增加钛的含量,将不能合成得到中孔结构的分子筛．     

TS-2钛硅分子筛合成原料和方法的改进

以硅溶胶为硅源,钛酸四丁酯为钛源,四丁基氢氧化铵（ＴＢＡＯＨ）为模板剂,采用改进的方法合成了高结晶度的ＴＳ２分子筛,并对所合成样品用ＦＴＩＲ,ＸＲＤ,ＳＥＭ,２９ＳｉＭＡＳＮＭＲ,ＩＣＰ和Ｎ２吸附等方法进行了结构表征．实验中发现原料内添加适量氨水可使产品晶粒减小,骨架钛含量增加,比表面积和孔容增大,有利于提高其催化活性．另外,将晶化后母液中的ＴＢＡＯＨ循环使用,也能得到结晶度高和催化性能良好的ＴＳ２．采用本文推荐的合成原料和方法可大幅度降低ＴＳ２的合成成本     

Role of complex defects in photocatalytic activities of nitrogen-doped anatase TiO(2)

Deep impurity states associated with a substitutional nitrogen at an oxygen site (N(O)) are believed to be the source of the visible-light absorption of nitrogen-doped titanium dioxide (TiO(2)). Our comprehensive study using density functional theory (DFT) plus onsite Coulomb interaction (U) reveals that a titanium atom at an interstitial site (Ti(i)) is highly mobile and strongly binds with N(O). Hybridizations of N p with Ti d states of Ti(i) give rise to a new band at the valence band edge, eliminating the hole-trapping centers originated from the deep N(O) states. The suggested mechanism explains the photocatalytic oxidation reactions as well as the visible-light absorption observed on N-doped anatase TiO(2).     

Hierarchically Organized Silica–Titania Monoliths Prepared under Purely Aqueous Conditions

Hierarchically organized silica–titania monoliths were synthesized under purely aqueous conditions by applying a new ethylene glycol‐modified single‐source precursor, such as 3‐[3‐{tris(2‐hydroxyethoxy)silyl}propyl]acetylacetone coordinated to a titanium center. The influence of the silicon‐ and titanium‐containing single‐source precursor, the novel glycolated organofunctional silane, and the addition of tetrakis(2‐hydroxyethyl)orthosilicate on the formation of the final porous network was investigated by SEM, TEM, nitrogen sorption, and SAXS/WAXS. In situ SAXS measurements were performed to obtain insight into the development of the mesoporous network during sol–gel transition. IR‐ATR, UV/Vis, XPS, and XAFS measurements showed that up to a Si/Ti ratio of 35:1, well‐dispersed titanium centers in a macro‐/mesoporous SiO₂ network with a specific surface area of up to 582 m² g^?1 were obtained. An increase in Ti content resulted in a decrease in specific surface area and a loss of the cellular character of the macroporous network. With a 1:1 Si/Ti ratio, silica–titania powders with circa 100 m² g^?1 and anatase domains within the SiO₂ matrix were obtained.     

Synthesis of Ti‐MCM‐41 directly from silatrane and titanium glycolate and its catalytic activity1

Titanium is successfully incorporated in hexagonal mesoporous silica to form Ti‐MCM41 at low temperature. Silatrane and titanium glycolate synthesized from the oxide one‐pot synthesis process are used as the precursors. Using the cationic surfactant cetyltrimethylammonium bromide as a template, the resulting meso‐structure mimics the liquid‐crystal phase. The percentage of titanium loading is varied in the range 1–35%. The temperatures used in the preparation are 60 °C and 80 °C. After heat treatment, very high surface area mesoporous silica was obtained and characterized using diffuse reflectance UV (DRUV) spectroscopy, X‐ray diffraction (XRD), BET surface area, X‐ray fluorescence, energy dispersive spectroscopy and transmission electron microscopy (TEM). At 35% titanium, the titanium atom is also in the framework showing the pattern of hexagonal mesostructure, as shown by DRUV, XRD and TEM results. The surface area is extraordinarily high, up to more than 2300 m² g^?1, and the pore volume is as high as 1.3 cm³ g^?1 for a titanium loading range of 1–5%. Oxidative bromination reaction using Ti‐MCM‐41 as catalyst showed impressive results, with the 60 °C catalysts having higher activity. Copyright © 2005 John Wiley & Sons, Ltd.     

Stepwise modification of titanium alkoxy chloride compounds by pyridine carbinol

The stepwise modifications of stoichiometric mixtures of titanium chloride (TiCl 4) and titanium iso-propoxide (Ti(OPr (i)) 4) by 2-pyridine methanol (H-OPy) led to the isolation of a systematically varied, novel family of compounds. The 3:1 reaction mixture of Ti(OPr (i)) 4:TiCl 4 yielded [Cl(OPr (i)) 2Ti(mu-OPr (i))] 2 ( 1). Modification of 1 with 1 and 2 equiv of H-OPy produced [Cl(OPr (i)) 2Ti(mu c-OPy)] 2 ( 2, where mu c = chelating bridge) and "(OPy) 2TiCl(OPr (i))" ( 3, not crystallographically characterized), respectively. Altering the Ti(OPr (i)) 4 to TiCl 4 stoichiometry to 1:1 led to isolation and identification of another dimeric species [Cl 2(OPr (i))Ti(mu-OPr (i))] 2 ( 4). Upon modification with 1 equiv of H-OPy, [Cl 2(OPr (i))Ti(mu c-OPy)] 2 ( 5) was isolated from toluene and (OPy)TiCl 2(OPr (i))(py) ( 6) from py. An additional equivalent of H-OPy led to the monomeric species (OPy) 2TiCl 2 ( 7). Because of the low solubility and similarity in constructs of these compounds, additional analytical data, such as the beryllium dome or BeD-XRD powder analyses, were used to verify the bulk samples, which were found to be in agreement with the single crystal structures.     

Au/Ti-SBA-15的制备及其催化CO氧化性能

采用气相键合法制备了表面经二氧化钛单层分布修饰的SBA-15材料,并以该材料为载体,用改进的原位沉积沉淀法制备了Au负载量为1%的系列催化剂(Au/Ti-SBA15),考察了它们在CO氧化反应中的催化性能.采用透射电镜、X射线衍射、N2吸附-脱附、紫外-可见漫反射吸收光谱、X射线荧光分析和电感耦合等离子体发射光谱等方法对修饰的载体及其负载金催化剂进行了表征.结果表明,SBA-15孔道对Au颗粒的生长起到很好的限制作用.制得的催化剂在广谱温度范围内均有良好的催化CO氧化活性,不仅在低温具有氧化活性,而且在高达500oC时CO转化率还能达到100%,催化剂的存储稳定性和重现性都较好.     

Influence of Ti addition on boehmite-derived aluminum silicate aerogels: structure and properties

Aluminosilicate aerogels offer potential for extremely low thermal conductivities at temperatures greater than 900?°C, beyond where silica aerogels reach their upper temperature use limits. Aerogels have been synthesized at two Al:Si ratios, a 3Al:1Si mullite composition, and an 8Al:1Si alumina rich composition. Boehmite (AlOOH) is used as the Al source, and tetraethoxysilane as the Si precursor. The influence of Ti as a ternary constituent, introduced through the addition of titanium isopropoxide in the sol?Cgel synthesis, on aerogel morphology and thermal properties is evaluated. Four different boehmite precursor powders are evaluated. Morphology, surface area and pore size, and thermal transformation vary with the crystallite size of the starting boehmite powder, as does incorporation of titanium and evolution of Ti-containing crystalline phases. The addition of Ti influences sol viscosity, gelation time, surface area and pore size distribution, as well as phase formation on heat treatment.