SBA-15负载Pd催化剂的制备及其在Heck反应中的应用研究

利用水热反应制备了表面离子液体功能化的SBA-15介孔材料,在丙酮溶液中与氯化钯反应,然后使用水合肼在乙醇中还原.测试了这种催化剂在Mizoroki-Heck反应中的催化活性.与直接负载在SBA-15上的钯催化剂相比,这种表面修饰的介孔SBA-15负载催化剂表现出更高的催化活性、可回收性和反应稳定性.氮气吸脱附实验和小角XRD衍射实验表明,在合成中,材料的介孔性能并没有被破坏.透视电镜也表征了该材料的表面形貌.最后,Mizoroki-Heck反应表明该催化剂具有很高的催化活性,且循环五次后,其催化活性降低并不明显.     

氨基功能化SBA-15的直接合成及其对CO_2的吸附性能研究

通过直接法合成了氨基功能化SBA-15介孔材料。使用X-射线粉末衍射法(XRD),N2吸-脱附,透射电子显微(TEM)等技术对氨基功能化材料进行了表征。实验结果表明:当反应原料中nAPTES/(nAPTES+nTEOS)≤0.20时,APTES功能化的材料都具有典型的介孔SBA-15结构;但当nAPTES/(nAPTES+nTEOS)≥0.225时,由于氨基对SBA-15结构的副作用导致SBA-15介孔结构坍塌。在氟离子辅助合成下可以获得高含量氨基(反应原料中nAPTES/(nAPTES+nTEOS)的比值为0.25)功能化的SBA-15材料,且此材料中的介孔孔径和BET比表面积都较大。CO2吸附结果表明,随着反应原料中APTES含量提高,所合成的材料对CO2的吸附量相应增加,同时在101kPa和25℃下,通过氟离子辅助合成的材料对CO2的吸附量远远优于无氟离子辅助合成材料的。本研究还对后嫁接法和直接合成法获得氨基功能化SBA-15介孔材料的优缺点进行了讨论。     

有序介孔胺化的聚合物材料的合成及在Knoevenagel缩合反应中的催化性能

通过氯化和胺化等手段对有序介孔聚合物材料(FDU-16)进行功能化, 成功地将胺基引入到介孔聚合物骨架中, 制备出新型有序介孔固体碱催化材料. X射线衍射(XRD)、 氮气吸附-脱附及透射电子显微镜(TEM)表征结果表明, 功能化后的固体碱材料依然保持高度有序性; 红外表征结果表明, 大量的胺基被引入到材料的骨架中. 在Knoevenagel缩合中, 这种新型有序介孔固体碱材料表现出比功能化的介孔二氧化硅等材料更高的催化活性, 这主要归因于其具有较高的比表面积、较强的碱性以及较多的活性中心.     

TEPA功能化SBA-15的CO_2吸附性能

以正硅酸乙酯(TEOS)为硅源,P123为模板剂,通过加入适量HAc及调整反应体系pH方式,采用水热及萃取法合成表面羟基含量较高的介孔SBA-15材料.以不同含量四乙烯五胺(TEPA)对SBA-15进行功能化,获得氨基功能化介孔SBA-15材料.利用X射线衍射(XRD)、N2吸-脱附、傅里叶红外光谱(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、元素分析等手段对材料结构性能进行表征.以不同含量TEPA功能化介孔SBA-15为吸附剂,对CO_2进行吸附,考察了吸附温度、CO_2浓度、水等对吸附效率的影响.实验结果表明,常温、常压下30%TEPA功能化介孔SBA-15的CO_2吸附量最高,且重复使用性能良好.     

HCl对有序介孔氧化硅结构与形貌的影响

以三嵌段共聚物P123为有机模板导向剂、正硅酸乙酯TEOS为无机硅源, 在HCl存在的强酸性环境下, 采用水热法合成了有序介孔分子筛SBA-15. 采用XRD、SEM、TEM、N2吸附-脱附等手段对产物的结构与形貌进行了分析, 考察了HCl用量对有序介孔材料结构及形貌的影响. 结果表明, 在合成有序介孔氧化硅时, HCl发挥了催化和中间离子的双重作用, 促使棒状胶束形成六方有序排列, 降低SBA-15中微孔的数量, 而且对合成有序介孔氧化硅SBA-15的形貌有显著影响. 适宜的HCl用量对形成“珍珠链状”形貌的、热稳定性优良的SBA-15介孔材料具有重要作用.     

功能化SBA-15的合成、表征及其在Knoevenagel缩合反应中溶剂效应的研究

利用后接枝法合成了含有N-丙基苄胺、N-丙基邻羟基苄胺、N-丙基对羟基苄胺功能化的SBA-15,通过傅里叶红外、X射线衍射、N2-吸附脱附、元素分析对功能化SBA-15的表征表明,功能化的SBA-15保持了规整有序的介孔孔道;同时考察了3种功能化SBA-15对Knoevenagel缩合反应的催化性能,结果表明,三种催化剂都具有较高的催化活性,在以乙醇为溶剂,50℃反应6h的条件下,苯甲醛和氰乙酸乙酯的反应产率均达到80%左右,在该反应体系中有明显的溶剂化效应,质子化溶剂更有利于Knoevenagel缩合反应的进行.     

氨基功能化SBA-15介孔分子筛的制备与表征

以3-氨丙基三乙氧基硅烷为偶联剂,采用后合成法对介孔分子筛(SBA-15)的表面进行改性,制得氨基功能化的介孔NH<,2>-SBA-15材料(简称NH<,2>-SBA-15),其结构和性能经FT-IR,元素分析,XRD,SEM及低温N<,2>吸附-脱附表征.结果表明,氨基成功地嫁接到SBA-15表面,含量高达3.47 ...     

一种新型有机-无机杂化介孔碱性催化材料的合成与表征

通过直接合成方法, 制备了胺基功能化的HMS型有机无机杂化介孔碱性催化材料(Amx-HMS).采用粉末X射线衍射分析、透射电镜、氮气吸附-脱附、29Si固体核磁共振、 红外光谱和元素分析等方法对合成材料进行了表征. 通过典型的2'-羟基苯基甲基酮和苯甲醛缩合制备黄烷酮的反应对其碱催化活性中心进行了表征.     

有序介孔二氧化硅对正丁醛的吸附性能

合成了一系列具有不同孔结构与性质的有序介孔二氧化硅材料SBA-15、MCM-41、SBA-16、KIT-6, 同时通过改变水热温度制备了不同孔径大小的SBA-15, 并利用小角X射线散射、透射电镜、扫描电镜和氮气吸附-脱附等手段, 对其介孔结构进行了表征. 以正丁醛为探针分子, 考察了其对有机醛的吸附, 并与Y-沸石的吸附性能做了对比. 结果表明, 材料的介孔比表面积与其对正丁醛的吸附量成正比, 吸附等温线符合Langmuir 模型, 属于单层吸附, 具有最大介孔比表面积的MCM-41对正丁醛的吸附量最大(484 mg·g^-1). 最后将SBA-15添加到卷烟滤嘴中, 实验结果表明, SBA-15能显著降低卷烟烟气中巴豆醛的释放量.     

一步法直接合成有机季铵功能修饰的介孔分子筛SBA-15

以P123 嵌段共聚物为模板剂, 3-三甲基丙基氯化铵三甲氧基硅烷(TMAPS)为修饰剂, 酸性条件下一步法直接合成了有机季铵基团功能修饰的SBA-15, 并通过XRD、TEM、N2吸附-脱附、Raman 光谱等对功能化样品的结构和性质进行了表征, 对一步法合成TMAPS 修饰的SBA-15 的可能反应机理进行了探讨. 修饰后的SBA-15 仍然保持了二维六方特征介孔结构, 随着TMAPS负载量的增大, SBA-15 孔道有序度下降, 孔径、孔容和比表面积也随之下降. 有机季铵基团在SBA-15 孔道表面均匀分散, 可与HAuCl4通过快速离子交换制备Au 颗粒高度分散的Au-SBA-15.     

Synthesis and characterization of surface modified SBA-15 silica materials and their application in chromatography

Hexagonally ordered SBA-15 mesoporous silica spheres with large uniform pore diameters are obtained using the triblock copolymer, Pluronic P123, as template with a cosurfactant cetyltrimethylammonium bromide (CTAB) and the cosolvent ethanol in acidic media. A series of surface modified SBA-15 silica materials is prepared in the present work using mono- and trifunctional alkyl chains of various lengths which improves the hydrothermal and mechanical stability. Several techniques, such as element analysis, nitrogen sorption analysis, small angle X-ray diffraction, scanning electron microscopy (SEM), FTIR, solid-state (29)Si and (13)C NMR spectroscopy are employed to characterize the SBA-15 materials before and after surface modification with the organic components. Nitrogen sorption analysis is performed to calculate specific surface area, pore volume and pore size distribution. By surface modification with organic groups, the mesoporous SBA-15 silica spheres are potential materials for stationary phases in HPLC separation of small aromatic molecules and biomolecules. The HPLC performance of the present SBA-15 samples is therefore tested by means of a suitable test mixture.     

Amino acid adsorption on mesoporous materials: influence of types of amino acids, modification of mesoporous materials, and solution conditions

In order to disclose the dominant interfacial interaction between amino acids and ordered mesoporous materials, the adsorption behaviors of five amino acids on four mesoporous materials were investigated in aqueous solutions with adjustable amino acid concentration, ion strength, and pH. The selected amino acids were acidic amino acid glutamic acid (Glu), basic amino acid arginine (Arg), and neutral amino acids phenylalanine (Phe), leucine (Leu), and alanine (Ala), and the selected mesoporous materials were SBA-15, Al-SBA-15, CH3(10%)-SBA-15, and CH3(20%)-SBA-15. The adsorption capacities of Glu and Arg were strongly dependent on pH and surface charge of the mesoporous adsorbent. The adsorption of Phe showed pH insensitivity but depended on the surface organic functionalization of mesoporous adsorbent. On the basis of the theoretical analysis about the interaction between amino acid and adsorbent, such a remarkable difference was attributed to the different nature of the interaction between amino acid and adsorbent. Arg could be readily adsorbed on the surface of SBA-15, especially Al-SBA-15, under appropriate pH in which the electrostatic interaction was predominant. The driving force of Phe adsorption on mesoporous adsorbent mainly came from the hydrophobic interaction. Therefore, the adsorption capability of Arg decreased with increasing ion strength of solution, while the adsorption capability of Phe increased with the increasing degree of CH3 functionalization on SBA-15. For neutral amino acid Phe, Ala, and Leu, the adsorption capability increased with the increase of the length of their side chains, which was another evidence of hydrophobic effect. Thus, all the adsorption of amino acids on mesoporous silica materials can be decided by the combined influence of two fundamental interactions: electrostatic attraction and hydrophobic effect.     

Synthesis of carboxyl-modified rod-like SBA-15 by rapid co-condensation

Carboxyl-modified SBA-15 rod-like mesoporous materials have been synthesized by a facile rapid co-condensation of tetraethylorthosilicate (TEOS) and 2-cyanoethyltriethoxysilane (CTES), followed by hydrolysis of cyanide groups in sulfuric acid. The concentration of carboxylic groups was varied by changing the silica source ratio of CTES/TEOS from 0.05 to 0.3. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the uniform ordered mesoporous structure and rod-like morphology of SBA-15 have been preserved even at the high concentration of carboxylic groups employed. Characterization by Fourier transformed infrared spectroscopy (FTIR), solid-state NMR investigation indicated that carboxylic groups have been successfully grafted onto the surface of SBA-15 through siloxane bonds [(O(3))SiCH(2)CH(2)COOH. The negative charges of the modified SBA-15 materials were enhanced by the presence of the carboxylic groups on the surface. The capacity of lysozyme adsorption of the modified SBA-15 materials were found to be significantly improved as compared with pure silica SBA-15. The maximum amount of lysozyme adsorption on carboxyl-modified was increased with the pH of solution increased from 5.5 to 9.0.     

Preparation, Characterization and Catalytic Performance of La-SO42-/SBA-15 in Esterification of Acetic Acid with n-Butanol

La-SO42-/SBA-15 was synthesized with various amounts of lanthanum via incipient-wetness impregnation.Characterization was done by X-ray diffraction(XRD), transmission electron micrographs(TEM), nitrogen adsorption,FTIR spectroscopic analysis, thermogravimetric analysis, and the total amount of acidity of catalyst was estimated by TPD of NH3. The results indicate that lanthanum has been incorporated into SBA-15 molecular sieve. The prepared materials(La-SO42-/SBA-15) keep the highly ordered mesoporous two-dimensional hexagonal structure and do not change the mesoporous channel structure of the support SBA-15. The catalyst showed best catalytic activity in the synthesis of n-butyl acetate. The optimum conditions of the esterification by orthogonal experiments were studied: the molar ratio of n-butanol to acetic acid 1:1.2, the amount of catalyst 7.5%, reaction time 80 min. The yield of n-butyl acetate could reach 93.2% under the optimum conditions. The catalyst was recyclable, cost effective and environmental friendly.     

Effects of Morphology and Structural Characteristics of Ordered SBA-15 Mesoporous Silica on Release of Ibuprofen

Three kinds of highly ordered SBA-15 mesoporous materials with different pore sizes and morphologies denoted as LPS-SBA-15 (stick-like with pore size 7.28 nm), CPS-SBA-15 (stick-like with pore size 5.96 nm) and T-SBA-15 (tablet-like with pore size 4.64 nm) have been prepared, characterized and employed as carrier materials. The release behaviors of the ibuprofen in a simulated body fluid from these mesoporous silica materials were studied. The influences of pore size and exterior morphologies of mesoporous silica on the release behaviors of ibuprofen have been investigated. It has been found that the release becomes fast with increasing of pore size and slow with extending of transport pathway, and that the release rate of ibuprofen from the three kinds of SBA-15 is LPS-SBA-15 > T-SBA-15 > CPS-SBA-15. The results show that the inner structure as well as the exterior morphologies of SBA-15 mesoporous silica can seriously affect the release behaviors of ibuprofen.     

C60/SBA-15介孔复合材料的合成及其荧光性质的研究

通过对介孔SBA-15孔壁氨基化(SBA-15-NH₂),然后与C₆₀反应形成化学键,成功地将C₆₀组装进入SBA-15孔道中,合成了C₆₀/SBA-15介孔复合材料.通过X射线衍射(XRD)、红外光谱(FTIR)、紫外-可见光谱(UV-V is)和差热-热重分析(TG-DTA)等方法对其进行了表征.同时,对复合材料的荧光性质进行了研究.结果发现,SBA-15-NH₂在575 nm处出现发射峰,C₆₀/SBA-15介孔复合材料在554 nm处出现发射峰,峰位蓝移21 nm.     

富含羧基的球形介孔分子筛SBA-15的合成及药物释放性能

本文采用原位合成法合成了富含羧基的SBA-15球形介孔分子筛. 研究了修饰剂（三烷氧基氰乙基硅烷 CTES）的用量对介孔分子筛SBA-15形貌、孔径及BET比表面积的影响. 用粉末X射线衍射(XRD)、扫描电镜(SEM)、红外（IR）和氮气吸附/脱附对样品进行了详细的表征. 该材料展示了尺寸在0.5-1 μm规则的球形形貌、有序的二维六方相介孔结构、较大的比表面积和孔容、并且随着修饰剂用量的增加, SBA-15的孔径变小, 比表面积下降. 药物组装及缓释性能测试表明, 该材料具有较好的药物组装及缓释释放性能. 该材料在催化、药物载体和色谱分析填料等领域将具有潜在的应用.     

Mesoporous SBA-15 materials modified with PW or W active species as catalysts for the epoxidation of olefins with H<Subscript>2</Subscript>O<Subscript>2</Subscript>

Five catalysts containing PW or W active species that anchored onto aminosilylated mesoporous silica SBA-15 by a post-grafting route were prepared and the resulting PW or W/APTES/SBA-15 hybrid materials were characterized by XRD, N₂ adsorption/desorption, surface area analysis, TEM, FT-IR, and ICP (inductively coupled plasma atomic emission spectroscopy). The names of these catalysts have been abbreviated as SBA-15m-a, SBA-15m-b, SBA-15m-c, SBA-15m-d, and SBA-15m-e according to the different active species. The PW or W active species were highly dispersed in the channels of the modified mesoporous materials. The interaction between PW or W species and amino groups grafted on the channel surface of SBA-15 led to the immobilization of PW or W species. Their catalytic activity in the epoxidation of cyclooctene with H₂O₂ as oxidant was investigated. Among them, SBA-15m-a showed the best performance, with 98.9% conversion and 98.4% selectivity. The catalyst could be reused for six times with a little decrease in activity.     

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, microstructure, and properties of novel low-κ brominated epoxy/mesoporous silica composites

Brominated epoxy resin (BER) composites containing various amounts of SBA-15 and SBA-16 types mesoporous silicas were prepared through the thermal curing with 3-methyl-tetrahydrophthalic anhydride, and their morphologies, dielectric constants (κ), thermal properties and mechanical properties were studied. The investigation suggested that the dielectric constant could be reduced from 4.09 of the pure thermosetting BER to 3.74 and 3.7 by incorporating 3 wt.% SBA-15 and SBA-16, respectively. The reduction of the dielectric constant is attributed to the incorporation of the air voids (κ = 1) stored within the mesoporous silica materials, the air volume existing in the gaps on the interfaces between the mesoporous silica and the BER matrix, and the free volume created by introducing large-sized domains. The BER/mesoporous silica composites also present stable dielectric constants across the wide frequency range. An improvement of thermal stability of the BER is achieved by incorporation of the mesoporous silica materials. The enhanced interfacial interaction between the surface-modified mesoporous silica and the BER matrix has also led to an improvement of the toughness.