多金属氧酸盐/TiO2介孔杂化材料的合成及光催化性能研究

采用蒸发诱导自组装法合成了介孔TiO2,并将表面含有Si-OH基团的钨磷酸盐衍生物(Bu4N)3PW11O39-[O(SiOH)2](TBAPW11Si2)嫁接到乙醇回流脱模的介孔TiO2上,合成了TBAPW11Si2/TiO2介孔杂化材料.采用IR、XRD、N2吸附-脱附、TEM、ICP-AES对样品的结构和组成进行了表征.结果表明,TBAPW11Si2与TiO2之间的共价键联是通过表面Si-OH和Ti-OH间的缩合进行的;TiO2表面足够的Ti-OH基团和一定温度的焙烧是这一缩合的必要条件.与TiO2载体相比,嫁接了TBAPW11Si2的杂化样品,锐钛矿相的结晶度略有增加;但表面积、孔容和孔径均有所减小,且随TBAPW11Si2负载量的增加而降低.光催化降解甲基橙的结果显示,杂化样品表现出比载体TiO2高得多的催化活性,甚至与高结晶度的商品光催化剂P25相当,显示出多金属氧酸盐-TiO2协同作用的优越性.     

Al~(3+)离子介入提升(NH_4)_2SiF_6对SBA-15介孔材料的水热稳定化作用（英文）

提出了一种(NH4)2Si F6处理提高SBA-15介孔材料水热稳定性的改良方法.采用SBA-15介孔材料中预引入Al3+离子,再进行1%SiO 2计量的(NH4)2Si F6处理,最后用强酸洗脱预引入的Al3+.结果显示,由此处理的SBA-15材料,其水热稳定性明显优于相同条件下未预引入Al3+时(NH4)2Si F6处理的样品.两者在800°C、100%水蒸气处理12 h后,虽然均能很好保持其介观有序度、形貌及六方孔道结构,但前者的比表面积可高达271 m2/g,而后者仅为224 m2/g.表明Al3+离子介入能大幅度提升(NH4)2Si F6处理对SBA-15介孔材料的稳定化作用.这主要得益于预引入的骨架Al3+在保障(NH4)2Si F6处理修复SBA-15材料表面缺陷和进行表面疏水化、提升其水热稳定性的同时,能减缓(NH4)2Si F6释放的多余F离子对SBA-15材料骨架的刻蚀破坏作用.Al3+离子介入的这种提升作用与其引入方式和SBA-15材料所经受的温度密切相关.     

PW_(11)/SBA-15介孔杂化材料的直接合成与表征

采用三嵌段共聚物EO20PO70EO20(P123)为模板剂,正硅酸乙酯(TEOS)和缺位Keggin型多金属氧酸盐Na7PW11O39(PW11)为无机前驱体,由共缩合法一步合成了PW11/SBA-15介孔杂化材料.通过红外(IR)光谱、紫外-可见漫反射光谱(UV-Vis/DRS)、X射线衍射(XRD)、低温N2吸附、透射电子显微镜(TEM)等手段对杂化材料和合成过程进行了表征.结果表明:杂化材料中不仅多金属氧酸盐的Keggin单元保留完整,且共价键联于介孔孔道内部,而且样品基本具有规整有序的六方介孔结构.TEOS预水解时间的长短对有序结构的构筑有明显影响,随预水解时间延长,样品的介观有序性增加.这是因为多金属氧酸盐对模板剂P123有盐析作用,其作用大小与多金属氧酸盐前驱物的溶解度有关.     

酸诱导介观相转变硅基介孔材料的合成机理及其改性

采用两步法以三嵌段共聚物P104(PEO27-PPO61-PEO27)为模板剂合成介孔材料, 研究了介孔材料结构随体系pH 值的变化, 探讨了体系中介观相转变的机理. 研究表明,随着pH 的升高, 发现体系中无机物种和模板剂所组成的介观相发生了转变,由P6mm 的SBA-15(pH=1.51-2.67)2D六角孔道结构转变为3D 蠕虫状孔道的MSU-X(pH=3.93-4.56)结构. 对所得的两种不同种类的硅基材料以γ-胺丙基三乙氧基硅烷(APTES: NH2(CH2)3Si(C2H5O)3)进行表面烷基化改性结果表明, 在同样的条件下, 经过改性后MSU-X类介孔材料孔壁上接枝的烷基数目要远超过SBA-15 类介孔材料.     

多金属氧酸盐/介孔分子筛杂化材料的制备与表征

采用嵌段共聚物模板P123和缺位Keggin结构的多金属氧酸盐K₈SiW₁₁O₃₉•12H₂O, 由溶胶-凝胶法合成了具有类六方结构的SiW₁₁/SBA-15杂化介孔分子筛材料, 并通过X射线衍射(XRD)、傅立叶变换红外光谱(FT-IR)、紫外漫反射光谱(UV/DRS)、电感耦合等离子原子发射光谱(ICP-AES)、低温N₂吸附、透射电子显微镜(TEM)等手段对其进行了表征. 结果表明, 杂化材料中不仅规整均一的类六方介孔结构得以保持, 而且多金属氧酸盐的Keggin单元保留完整(含量达25%左右), 并共价键联于介孔材料的孔道内部. 稳定性实验表明, 杂化材料中多金属氧酸盐在水中的流失率远低于一般浸渍法制备的样品.     

共价嫁接Ru(Ⅱ)配合物杂化材料的制备及氧气传感性能研究

利用十六烷基三甲基溴化铵制备了一种具有MSU型蠕虫状孔道结构, 同时共价嫁接了Ru(Ⅱ)配合物的介孔杂化功能材料, 并研究了其氧气传感性能. 双功能有机改性硅酸酯Bpy-Si不仅是配合物Ru(bpy)2Cl2·2H2O的一个配体, 而且通过与正硅酸乙酯的水解和共聚反应, 把Ru(bpy)2(bpy-Si)Cl2配合物通过Si—C共价键嫁接到二氧化硅的骨架上. 研究结果表明, Ru(Ⅱ)分子在杂化材料中的发光受氧气猝灭明显, 而且具有较快的响应时间, 所得材料具有作为性能优良的氧气传感材料研究的潜质. 由于介孔材料的独特孔道结构有利于氧气在载体中的扩散, 介孔样品表现出比无定形样品更高的灵敏度.     

具有MFI骨架结构的介孔钛硅材料的合成、表征和催化性能

利用介孔碳作硬模板合成出具有MFI骨架结构的介孔钛硅材料. 该样品复制了类似SBA-15的介孔结构, 同时骨架含有MFI微孔结构. 透射电镜表征结果表明, 样品表面还有部分大孔结构. 催化结果证明了该样品既具有介孔材料较大孔道结构, 又保持了微孔钛硅材料的高活性.     

共价嫁接钌(Ⅱ)配合物SBA-15介孔分子筛的光学氧传感行为

使用P123(EO20PO70EO20)作为表面活性剂, 并通过正硅酸乙酯与含可以水解烷氧基团的[Ru(Phen)2Phen—Si]2+功能化配合物的水解和共缩聚反应, 成功地制备了共价嫁接[Ru(Phen)3]2+分子片断的复合SBA-15介孔杂化材料. 用红外光谱和发光强度猝灭Stern-Volmer曲线对样品进行了表征, 并分别用Demas双格位模型以及Lehrer模型对所获得的复合Ru-SBA-15样品的Stern-Volmer曲线进行了拟合. 实验结果表明, 所制备的传感样品对氧气具有较高的传感灵敏度. 发光分子与分子筛之间产生强有力的CH2—Si化学键使得该杂化材料具有可逆的氧传感信号和较好的光化学稳定性.     

Cu-Zn-Zr/SBA-15介孔催化剂的制备及CO2加氢合成甲醇的催化性能

以具有骨架结构的SBA-15介孔分子筛为载体,采用浸渍法合成了具有高比表面积、不同金属氧化物含量的Cu-Zn-Zr介孔催化剂CZZx/SBA-15(x=0.3,0.4,0.5,0.6).采用N2吸附-脱附(BET)、X射线衍射(XRD)、H2程序升温还原(H2-TPR)、CO2吸附(CO2-TPD)和透射电子显微镜(TEM)等手段对样品进行了表征.在固定床反应器上评价了其CO2加氢合成甲醇的催化性能.实验结果表明,CZZx/SBA-15催化剂具有介孔结构,负载的Cu O,Zn O和Zr O2能够很好地分散在表面,并且负载氧化物晶粒尺寸不同.催化剂的铜比表面积SCu与甲醇催化活性呈近似线性关系,其中CZZ0.4/SBA-15催化剂表现出最大甲醇选择性(54.32%),与CZZ相比,甲醇选择性增加24.85%.随着金属氧化物负载量的增大,催化剂比表面积和SCu明显减小,甲醇选择性与收率也相应减小,负载型CZZx/SBA-15催化剂表面结构对CO2加氢合成甲醇反应活性起关键作用.     

Co-B/SBA-15非晶态催化剂应用于肉桂醛选择性加氢的研究

以介孔材料SBA-15作为载体,采用浸渍法制备Co-B/SBA-15非晶态催化剂,该样品仍然保持SBA-15特有的有序规整孔道结构,Co-B非晶态合金颗粒均匀分布在孔道内壁,采用普通SiO2载体制备的Co-B/ SiO2,Co-B颗粒主要分布在外表面.在肉桂醛选择性加氢制肉桂醇中,Co-B/SBA-15的催化活性和对肉桂醇的最佳得率显著高于Co-B/SiO2,主要归因于活性位的高分散,规整的孔道结构,以及独特的活性位团簇结构和电子态.     

Photochromic ordered mesoporous hybrid materials based on covalently grafted polyoxometalates

Novel polyoxometalate (POM)-grafting mesoporous hybrid silicas, XW(11)/MHS (X=P, Si) and TBAPW(11)Si(2)/MHS, have been prepared respectively by co-condensation and post-synthesis routes based on the employment of Keggin-type monovacant XW(11) or a Si-substituted compound TBAPW(11)Si(2) as POM precursors. Upon characterization of the samples by FT-IR, XRD, ICP-AES, TEM and N(2) adsorption-desorption measurement, it was found that Keggin units were retained perfectly in ordered hexagonal mesopore channels with SBA-15 architecture and immobilized by covalent linkages on the mesopore wall. These materials, especially the co-condensed samples, exhibited stable and reversible photochromic properties under UV irradiation although no special organic component was supplied additionally as an electron donor. An investigation of the photochromism revealed that the photochromic response depended on the centre atom of the POM species (i.e., the redox potential of the POM), the content of the POM and the synthetic route of the sample, while the bleaching process was correlated not only to the redox potential but also to the pore size of the sample. The photochromic mechanism was also studied in detail by cyclic voltammetry, ESR, FT-IR and XPS techniques. It was found that the remaining P123 template acted as a reducing agent and was oxidized during the photochromic process accompanied by the reduction of the POM to heteropolyblue. Thus, a close contact between the POM and the remaining P123 chain in the sample is necessary. Low close-contact degree results in poor photochromic behavior of the post-synthesized sample and impregnated samples.     

Synthesis, characterization, and luminescence properties of the ternary europium complex covalently bonded to mesoporous SBA-15

A novel mesoporous SBA-15 type of hybrid material (phen-SBA-15) covalently bonded with 1,10-phenanthroline (phen) ligand was synthesized by co-condensation of tetraethoxysilane (TEOS) and the chelate ligand 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline (phen-Si) in the presence of Pluronic P123 surfactant as a template. The preservation of the chelate ligand structure during the hydrothermal synthesis and the surfactant extraction process was confirmed by Fourier transform infrared (FTIR) and (29)Si MAS NMR spectroscopies. SBA-15 consisting of the highly luminescent ternary complex Eu(TTA)(3)phen (TTA = 2-thenoyltrifluoroacetone) covalently bonded to a silica-based network, which was designated as Eu(TTA)(3)phen-SBA-15, was obtained by introducing the Eu(TTA)(3).2H(2)O complex into the hybrid materials via a ligand exchange reaction. XRD, TEM, and N(2) adsorption measurements were employed to characterize the mesostructure of Eu(TTA)(3)phen-SBA-15. For comparison, SBA-15 doped with Eu(TTA)(3).2H(2)O and Eu(TTA)(3)phen complexes and SBA-15 covalently bonded with a binary europium complex with phen ligand were also synthesized, and were named SBA-15/Eu(TTA)(3), SBA-15/Eu(TTA)(3)phen, and Eu-phen-SBA-15, respectively. The detailed luminescence studies on all the materials showed that, compared with the doping sample SBA-15/Eu(TTA)(3)phen and binary europium complex functionalized sample Eu-phen-SBA-15, the Eu(TTA)(3)phen-SBA-15 mesoporous hybrid material exhibited higher luminescence intensity and emission quantum efficiency. Thermogravimetric analysis on Eu(TTA)(3)phen-SBA-15 demonstrated that the thermal stability of the lanthanide complex was evidently improved as it was covalently bonded to the mesoporous SBA-15 matrix.     

Preparation and characterization of tungsten carbide confined in the channels of SBA-15 mesoporous silica

A series of WO3/SBA-15 materials with different Si/W ratios have been prepared by impregnating the host material SBA-15 with aqueous ammonium paratungstate solutions. After temperature-programmed carburization (TPC) in flowing CH4/H2 (20/80 v/v mixture), the materials are converted to the corresponding W2C/SBA-15 species. Both the oxide and carbide materials are characterized using X-ray diffraction, nitrogen adsorption-desorption, 29Si NMR spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and TEM measurements. The XRD results show that after impregnation with different amounts of tungsten and subsequent carburization, the materials retain the mesopore structure of SBA-15. The nitrogen adsorption-desorption results indicate that a thin layer of W2C covers the internal walls of SBA-15. Quantitative 29Si single-pulse excitation MAS experiments and FTIR spectroscopy show that the incorporation of W2C in the channels of SBA-15 is correlated with the formation of Si-O-W bonds. Some Si-O-W bonds are transformed into Si-O-H bonds after carburization. The TEM results show that the thickness of the W2C thin layer is 1.7-1.9 nm in W2C/SBA-15. A model involving a discrete W2C thin layer in the channels of SBA-15 is proposed on the basis of the NMR data. The calculated thickness of the discrete W2C thin layer is consistent with value given by HRTEM.     

Preparation and Characterization of Divanadium Pentoxide Nanowires inside SBA-15 Channels

One-dimensional V2O5 nanowires have been synthesized inside the channels of mesoporous silica SBA-15 through chemical approach, which involves aminosilylation of silanol groups on the silica surface, anchoring of isopoly acid, H6V10O28, by neutralization of basic amine groups, and thermal decomposition. The formation and physicochemical properties of the nanowires were monitored and studied by TG-DTA, variable temperature in situ XRD, TEM, N2 sorption measurements and UV-Vis DRS. The results indicate that V2O5 nanowires formed within SBA-15 channels belong to orthorhombic polycrystal domains. The oxygen-to-metal charge transfer band of V2O5 nanowires shows a blue shift in comparison with bulk V2O5, which clearly exhibits the quantum size effect of nanowires.     

Design of heterogeneous catalysts via multiple active site positioning in organic-inorganic hybrid materials

Catalytic materials bearing multiple sulfonic acid functional groups and positioned at varying distances from one another on the surface of mesoporous solids are prepared to explore the effects that the spatial arrangement of active sites have on catalytic activity and selectivity. A series of organosiloxane precursors containing either disulfide or sulfonate ester functionalities (synthons of the eventual sulfonic acid groups) are synthesized. From these molecular precursors, a variety of organic-inorganic hybrid, mesostructured SBA-15 silica materials are prepared using a postsynthetic grafting procedure that leads to disulfide and sulfonate ester modified silicas: [Si]CH(2)CH(2)CH(2)SS-pyridyl, 2.SBA, [Si]CH(2)CH(2)CH(2)SSCH(2)CH(2)CH(2)[Si], 3.SBA, [Si]CH(2)CH(2)(C(6)H(4))(SO(2))OCH(2)CH(3), 4.SBA, and [Si]CH(2)CH(2)(C(6)H(4))(SO(2))OC(6)H(4)O(SO(2))(C(6)H(4))CH(2)CH(2)[Si], 6.SBA ([Si] = (tbd1;SiO)(x)()(RO)(3)(-)(x)()Si, where x = 1, 2). By subsequent chemical derivatization of the grafted species, thiol and sulfonic acid modified silicas are obtained. The materials are characterized by a variety of spectroscopic ((13)C and (29)Si CP MAS NMR, X-ray diffraction) and quantitative (TGA/DTA, elemental analysis, acid capacity titration) techniques. In all cases, the organic fragment of the precursor molecule is grafted onto the solid without measurable decomposition, and the precursors are, in general, attached to the surface of the mesoporous oxide by multiple siloxane bridges. The disulfide species 2.SBA and 3.SBA are reduced to the corresponding thiols 7.SBA and 8.SBA, respectively, and 4.SBA and 6.SBA are transformed to the aryl sulfonic acids 11.SBA and 12.SBA, respectively. 7.SBA and 8.SBA differ only in terms of the level of control of the spatial arrangement of the thiol groups. Both 7.SBA and 8.SBA are further modified by oxidation with hydrogen peroxide to produce the alkyl sulfonic acid modified materials 9.SBA and 10.SBA, respectively. The performances of the sulfonic acid containing SBA-15 silica materials (with the exception of 12.SBA) are tested as catalysts for the condensation reaction of phenol and acetone to bisphenol A. The alkyl sulfonic acid modified material 10.SBA derived from the cleavage and oxidation of the dipropyl disulfide modified material 3.SBA is more active than not only its monosite analogue 9.SBA, but also the presumably stronger acid aryl sulfonic acid material 11.SBA. It appears that a cooperative effect between two proximal functional groups may be operating in this reaction.     

Copolymers with fluorescence properties in mesoporous silica SBA-15:Synthesis and characterization

A novel copolymer with fluorescence properties in mesoporous silica SBA-15 was prepared via a combination of surface-initiated reversible addition-fragmentation chain transfer(RAFT) polymerization and "click" chemistry.A sufficient amount of peroxide groups were introduced into mesoporous silica SBA-15 channel pores and were further used to initiate the RAFT polymerization of styrene and 4-vinylbenzyl azide,resulting in SBA-15 supported polystyrene-co-poly(4-vinylbenzyl azide) copolymer(PS-co-PVBA/SBA-15) hybrid material.The samples were characterized by Fourier transform infrared spectroscopy(FT-IR),transmission electron microscopy(TEM),thermogravimetry analysis(TGA),N_2 adsorption-desorption isotherms and X-ray diffraction(XRD),respectively.The results show that the styrene and 4-vinylbenzyl azide had copolymerized inside mesoporous silica SBA-15.Subsequently,Npropargyl-carbazole(PC) was connected to PS-co-PVBA/SBA-15 hybrid material via "click" reaction,resulting in PS-co-PVBC/SBA-15 with carbazole side groups hybrid material.The fluorescence spectrum is dominated by a broad band from 350 nm to 400 nm in narrow region and the maximum peak is 362 nm,indicating the characteristic absorption of the carbazole group of PS-co-PVBC/SBA-15 hybrid material.     

Fe3O4@mesoporous SBA-15: a robust and magnetically recoverable catalyst for one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones via the Biginelli reaction

A magnetic nanoparticle conjugated mesoporous nanocatalyst (Fe(3)O(4)@mesoporous SBA-15) with a high surface area has been synthesized by chemical conjugation of magnetite (Fe(3)O(4)) nanoparticles with functionalized mesoporous SBA-15. Functionalized mesoporous SBA-15 containing surface carboxyl and amino groups was synthesized via the thiol-ene click reaction of cysteine hydrochloride and vinyl functionalized SBA-15. The catalytic activity of the robust, safe and magnetically recoverable Fe(3)O(4)@mesoporous SBA-15 nanocatalyst was evaluated in the Biginelli reaction under mild conditions for the synthesis of a diverse range of 3,4-dihydropyrimidin-2(1H)-ones. The separation and reuse of the Fe(3)O(4)@mesoporous SBA-15 nanocatalyst were simple, effective and economical.     

纯硅介孔分子筛SBA-15表面的手性移植

聚环氧乙烯醚-聚环氧丙烯醚-聚环氧乙烯醚(EO20PO70EO20)三嵌段高分子为模板剂制备了SBA-15分子筛. 用3-氨丙基-三乙氧基硅烷对SBA-15进行改性, 改性后SBA-15表面上的氨基再与(+)-O,O'-二苯甲酰基-L-酒石酸酐(DBTA)进行酰化反应, 以酰胺键将该手性羧酸连接在SBA-15表面上. XRD和氮气吸附结果表明, 材料经过处理后仍然保持良好的孔性质; 13C和29Si魔角旋转核磁共振(MAS NMR)谱图表明, SBA-15与氨丙基化合物的作用是共价成键, 表面修饰度达25%; 从傅里叶变换红外(FTIR) 光谱可见, 有部分修饰氨基与DBTA成功地进行了酰化反应, 以一个羧基裸露的形式将该二元羧酸化合物连接在表面上; 从孔径分布图可知, 胺丙基修饰之后孔减小了1.5 nm, 与DBTA修饰后孔尺寸又减少0.5 nm, 说明胺丙基化合物是头对头垂直连接在Si表面上, 而酒石酸分子是采取平行方式侧卧在氨基表面.     

Phenylboronic acid functionalized SBA-15 for sugar capture

The synthesis and characterization of organic-inorganic hybrid materials that selectively capture sugars from model biomass hydrolysis mixtures are reported. 3-Aminophenylboronic acid (PBA) groups that can reversibly form cyclic esters with 1,2-diols, and 1,3-diols including sugars are attached to mesoporous SBA-15 via different synthetic protocols. In the first route, a coupling agent is used to link PBA and SBA-15, while in the second route poly(acrylic acid) brushes are first grafted from the surface of SBA-15 by surface-initiated atom transfer radical polymerization and PBA is then immobilized. The changes in pore structure, porosity, and pore size due to the loading of organic content are measured by powder X-ray diffraction and nitrogen porosimetry. The increase in organic content after each synthesis step is monitored by thermal gravimetric analysis. Fourier transform infrared spectroscopy and elemental analysis are used to characterize the chemical compositions of the hybrid materials synthesized. D-(+)-Glucose and D-(+)-xylose, being the most commonly present sugars in biomass, are chosen to evaluate the sugar adsorption capacity of the hybrid materials. It is found that the sugar adsorption capacity is determined by the loading of boronic acid groups on the hybrid materials, and the hybrid material synthesized via route two is much better than that through route one for sugar adsorption. Mathematical modeling of the adsorption data indicates that the Langmuir model best describes the sugar adsorption behavior of the hybrid material synthesized through route one, while the Freundlich model fits the data most satisfactorily for the hybrid material prepared via route two. The adsorption kinetics, reusability, and selectivity toward some typical chemicals in cellulose acidic hydrolysis mixtures are also investigated.