介孔二氧化硅负载磷钨杂多酸催化合成聚四氢呋喃

采用浸渍法制备了介孔二氧化硅(SiO2)负载的磷钨杂多酸(PW12)催化剂(PW12/SiO2),其物化性质和表面酸强度经BET,IR,TG-DTG和Hammett指示剂法表征.以PW12/SiO2催化四氢呋喃开环聚合合成聚四氢呋喃(PTHF),考察了PW12的负载量[w(PW12)]和焙烧温度对催化剂活性的影响.实验结果表明,在w(PW12)为35.0%,于230 ℃焙烧活化3 h的条件下制备的催化剂(35Cat)活性最高.以35Cat为催化剂,用量占反应物总质量的15.0%时,PTHF收率达60.2%.     

Atom Transfer Radical Polymerization of Styrene and Methyl Methacrylate from Mesoporous Ordered Silica Particles

Summary: Mesoporous silica was used as substrate for the grafting of alkyl halides initiators. The control over the surface‐initiated polymerization of styrene and MMA, in terms of molar mass and molar mass distribution, was successfully achieved using an ATRP mechanism. The occurrence of the polymerization inside the mesopores was confirmed by thermogravimetric analysis.

Transmission electron microscopy and schematic representation of mesoporous silica functionalized by the anchored iniator (left) and the grafted polymer (right).     

介孔SiO2负载的纳米金及其催化应用

金（Au）的催化作用已成为催化领域的前沿研究课题。本文综述了近年来采用不同方法制备介孔二氧化硅(MCM-41, MCM-48, SBA-15)负载的纳米Au催化剂以及在CO低温氧化、环己烯加氢和环己烷氧化等反应中的催化作用。讨论了影响纳米Au催化剂活性的相关因素, 包括载体的种类、表面性质、Au纳米颗粒的尺寸、分散度以及稳定性等。最后对各种制备纳米Au的方法进行了总结。     

Immobilization of Pd Catalysts on Mesoporous Silica for Amine- and Copper-Free Sonogashira Coupling Reactions

Immobilization of catalysts on solid supports is a promising approach to combine the advantages of heterogeneous and homogeneous catalysts. Pd(PPh₃)₂Cl₂, known as an extremely active homogeneous catalyst for the Sonogashira coupling reaction, has been immobilized on high-surface-area MCF (mesocellular foams)–type mesoporous silica powder modified with 3-aminopropyltriethoxysilane and subsequently with diphenylphosphine. The functionalized MCF-type silica and supported catalysts have been characterized by x-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), elemental analysis, nitrogen sorption porosimetry, and scanning electron microscopy (SEM). Such supported Pd catalysts have proven to be useful recyclable reagents for copper- and amine-free Sonogashira coupling reactions of haloaromatic compounds with terminal alkynes.     

二氧化硅负载[C5Me5]2SmMe(THF)引发甲基丙烯酸甲酯聚合

近年来 ,有许多文献报道茂金属催化剂的负载化及其在烯烃聚合中的应用 ,这对发展新型茂金属催化剂和开发新型高分子材料有重要意义 [1,2 ] .我们 [3]曾报道壳聚糖负载稀土催化剂用于甲基丙烯酸甲酯的配位聚合有优良性能 .以五甲基环戊二烯为配体的有机稀土配合物 ,如 [Sm H( C5Me5) ]2 ,[C5Me5]Ln Me( THF) ( Ln=Sm,Yb)等在甲苯中单组分引发甲基丙烯酸甲酯聚合及内酯开环聚合具有许多优异性能[4 ,5] ,但是经负载化的该类催化剂的聚合性能尚未见报道 .本文报道将 [C5Me5]2 Sm Me·( THF)负载于二氧化硅 ,引发甲基丙烯酸甲酯聚合的结…     

溶胶-凝胶法构筑介孔二氧化硅纳微结构

基于硅酸脂水解/缩合的溶胶-凝胶法是目前制备SiO₂胶体最为常用的化学方法. 在溶胶-凝胶反应过程中, 引入介孔导向剂(通常是表面活性剂)可以得到具有介孔结构的SiO₂胶体. 通过对硅酸脂在多相体系界面水解/缩合过程的调控, 可以构筑具有不同纳微结构的介孔SiO₂材料, 为拓展介孔SiO₂材料的应用领域提供了新机遇, 同时也丰富了对溶胶-凝胶法的理解和认识. 本文综述了利用溶胶-凝胶法构筑介孔SiO₂纳微结构的最新研究进展, 并介绍了其在生物医药、 催化、 吸附分离等领域的应用前景, 最后对这一领域所面临的问题和未来发展方向进行了总结和展望.     

利用廉价硅酸盐为硅源合成介孔SiO2球

利用廉价的硅酸盐为二氧化硅前驱体,以非离子和阳离子表面活性剂为混合模板剂合成微米级的介孔二氧化硅。控制非离子和阳离子表面活性剂的量可以得到分散性较好的介孔二氧化硅球,其平均颗粒直径为2．5μm,平均孔径为3．25nm,比表面为1379m^2／g,孔体积高达1．12cm^3／g。实验讨论了两种表面活性剂的比例对介孔二氧化硅形貌和介相结构的影响,并用混合模板机理解释了不同形貌形成的原因。     

Controlled Radical Polymerization of Methyl Methacrylate Catalyzed by Hybrid Supported Iron Catalyst

A supported iron catalyst, which was prepared by anchoring FeCl2/FeCl3 on the cross-linking macroporous polyacrylate ion exchange resin, was evaluated via the controlled radical polymerization. When a small amount of CuCl2/ Me6TREN was added, the controllability of the polymerization over the iron-mediated catalyst was significantly improved（Mw/Mn = 1.23-1.73 ）, affording a polymer with a low residual metal via a simple catalyst separation procedure. After suitable regeneration, the supported iron catalyst could also he recycled. UV-Vis analysis showed that the additional copper catalyst could facilitate the radical deactivation process.     

巯丙基功能化介孔纳米二氧化硅的合成

用三种不同的方法将巯基丙基三甲氧基硅烷(MPTMS)引入二氧化硅网络中, 合成了粒径为50-200 nm的巯丙基功能化的介孔纳米二氧化硅, 并利用透射电子显微镜, 热重分析等手段对其形貌与性能进行了表征. 在巯丙基官能团的作用下介孔纳米二氧化硅的形貌发生了重大改变, 由非常规则的六角形变为纳米棒. 控制反应时间可以调节介孔纳米二氧化硅的粒径大小, 用三乙醇胺代替氢氧化钠可以合成直径在100 nm以下的功能化介孔二氧化硅粒子. 为了保护巯基官能团, 选用了酸醇提取法去除模板. 另外, 对介孔二氧化硅粒子的形成机制也进行了探讨.     

Ruthenium Complex Immobilized on Mesoporous Silica as Recyclable Heterogeneous Catalyst for Visible Light Photocatalysis

Aldehyde group-functionalized [Ru（bpy）2L]（PF6）2 catalyst was prepared and immobilized onto the mesoporous silica nanoparticles to act as a heterogeneous catalyst for the selective oxidation of thioanisole to methyl phenyl sulfoxide under visible light.The heterogeneous catalyst can be easily recovered by simple centrifugation without chemical treatment,exhibiting comparable catalytic efficiency with homogeneous ones and no decrease in catalytic efficiency after at least 5 cycles.     

介孔硅材料及其负载型催化剂去除挥发性有机物的最新进展

介孔硅材料由于具有大的比表面积,均一的孔结构和大的孔径,常被用于分离、吸附和催化等领域.本文综述了近年来国内外介孔硅材料及其负载型催化剂去除各类挥发性有机物(VOCs)的研究进展,主要包括烃类、甲醇、甲醛、丙酮、苯、甲苯、萘、乙酸乙酯等.讨论了介孔硅材料的结构对VOCs吸附过程的影响;介绍了不同催化剂消除各类VOCs的催化性能及反应机理,并重点评述了甲苯在不同催化剂上的研究进展.分析结果表明,介孔硅材料的表面环境、孔道结构以及宏观形貌是影响VOCs分子在介孔硅材料上吸附的主要因素;贵金属催化剂的应用需要提高其抗中毒性以及降低成本;过渡金属的研究应着重于研发高活性的负载型过渡金属复合氧化物催化剂.最后对国内外介孔硅材料及其负载型催化剂的发展进行了展望,今后催化剂的设计可以从“氧化硅载体”和“介孔孔道”两个方面展开,这将为设计合适的催化剂处理各类VOCs污染物提供一定参考.     

“Noodle-like” Mesoporous Silica Templated by Polyelectrolyte／Surfactant Complex

“Noodle-like” mesoporous silica with a diameter of about 180 nm and a length of ca. 10μm was prepared through sol-gel process by using poly(sodium 4-styrenesulfonate) (PSS)/cetyltrimethylammonium bromide (CTAB) complex as template. Parallel oriented regular mesopores with a diameter of around 2-4 nm are distributed along the wall of the particles, while the “worm-like” disordered mesopores can be found in the fringe part. This approach provides a new series of templates and a novel route to prepare inorganic mesoporous materials with special morphology.     

核酸适配体封盖的介孔二氧化硅纳米颗粒用于肌红蛋白的检测

利用核酸适配体封盖的介孔二氧化硅纳米颗粒构建了一种新型、 简便及免标记的肌红蛋白定量检测方法. 首先, 用肌红蛋白核酸适配体将荧光小分子罗丹明6G封盖在介孔颗粒内, 当存在目标物肌红蛋白时, 由于介孔颗粒上的核酸适配体可特异性结合肌红蛋白而脱离介孔颗粒表面, 进而释放介孔颗粒内的罗丹明6G, 使溶液荧光强度增强. 实验结果表明, 荧光强度与肌红蛋白的浓度呈正相关, 通过荧光强度的变化可实现对肌红蛋白的定量检测. 该方法的检出限低至1.1 nmol/L, 且选择性好, 可满足临床医学的检测要求.     

Mini Review: Electroanalytical Sensors of Mesoporous Silica Materials

Mesoporous silica materials are promising substrates for electroanalytical sensors and electrocatalysis. Their characteristics include uniform pore sizes, surface areas in excess of 1000 m² g^?1, and long-range ordering of the packing of pores. The size scale, aspect ratio, and properties of mesoporous silica provide advantages in a variety of sensor applications. To improve performance, miniaturize platforms, and expand applications for trace analysis, novel materials with high sensitivity and rapid response have been developed and employed in recent years. These materials include pure mesoporous silica, mesoporous silica functionalized with organic groups, and composite or hybrid mesoporous silica. In this review, recent advances are outlined involving the application of mesoporous silica-based materials in electroanalytical sensors.     

助表面活性剂对介孔二氧化硅孔径的影响

在十六烷基三甲基溴化铵(CTAB)与硝酸形成的胶束体系中,分别加入正戊醇与正辛胺作助表面活性剂,合成出介孔二氧化硅.经小角XRD和N₂气体吸附与脱附实验证实,随着CTAB与正戊醇摩尔比的增加,介孔二氧化硅的孔径增加;而随CTAB与正辛胺摩尔比的增加,介孔二氧化硅的孔径减小.主要原因是正戊醇增大了CTAB胶束体积,从而导致介孔二氧化硅的孔径增加.而在CTAB与正辛胺的混合胶束中,正辛胺同硅酸盐作用力比CTAB强,导致介孔二氧化硅的孔径减小.     

Influence of Silica Support Size on the Polymerisation of Ethylene Using a Supported Metallocene Catalyst

In the current work, we will focus on the influence of support properties on the activity and molecular weights of polyethylene produced with a metallocene supported on silica treated with MAO. It is demonstrated that relatively small changes in the size of the silica particles have a profound effect on the activity of the growing particles, and that not all particles in a given batch of catalyst behave in the same manner.     

Synthesis of Mesoporous Silica Molecular Sieves via a NovelTemplating Scheme

ThediscoveryofM41SfamilyofmesoporousmolecularsievesbyMobilresearchersI'2hasstimulatedconsiderableinterestintheuseofthesematerialsascatalysts,catalystsupports,aswellasadsorbents3'#.Intheoriginalreport"=,MCM-41waspreparedfromaself-assemblyprocesswhichinvolveselectrostaticinteractionsbetweenpositivelychargedquaternaryammoniummicelles(S )andinorganicanions(l-)usedasframeworkprecursors.Huoetal5extendedtheelectrostaticassemblyapproachesbyproposingfourcomplementarysynthesisschemes(S l-,S-I ,S X-…     

Characteristics of Titanocene Catalyst Supported on Palygorskite for Ethylene Polymerization

Due to the technical problems observed for homogeneous metallocene catalysts, such as reactor fouling and requirement for large amount of expensive methylaluminoxane (MAO) as cocatalyst, the development of supported metallocene catalysts is very important…     

Mesoporous Silica MCM‐41 Supported N‐Heterocyclic Carbene‐Pd Complex for Heck and Sonogashira Coupling Reactions

Heterocyclic carbene‐Pd complex was anchored onto the mesoporous silica MCM‐41 which exhibits high catalytic activity in Heck reaction under phosphine free reaction conditions for the reaction of iodo/bromoarenes with olefinic compounds such as butyl acrylate, isopropyl acrylate and styrene. This catalytic system also showed high activity for Sonogashira coupling reaction of various aryl halides under copper, phosphine and solvent‐free reaction conditions. The air and thermally stable catalyst were reused several times without significant loss of its activity. High efficiency of the catalyst along with its recycling ability and the rather low Pd‐loading demonstrated in both Heck and Sonogashira coupling reactions are the merits of the presented catalyst system.     

co-Condensation Synthesis of Salicylaldimine Calcium Complex Containing Mesoporous Silica Nanoparticles as Carriers for Drug Release

A series of functional mesoporous silica nanoparticles（MSNs） was synthesized by a one-step simple synthesis approach involving co-condensation of tetraethoxysilane（TEOS） and salicylaldimine ligand（Sal-Si） in the presence of cetyltrimethylammonium chloride（CTAC） under basic conditions.The target MSNs with different sizes （50,100 and 200 nm,respectively） were obtained.Furthermore,the Ca^2＋ cations were also introduced into MSNs.The prepared nanoparticles were characterized by means of infrared（IR） spectra,thermogravimetric analysis（TGA）,inductively coupled plasma（ICP）,CHN elemental analysis,nitrogen adsorption-desorption,scanning electron microscope（SEM） and transmission electron microscope（TEM）.Ibuprofen（IBU） which contains carboxyl groups was selected as a model drug.The results of drug loading and release reveal that the loading capacities and release behaviors of the model drug are highly dependent on the Ca^2＋ cations in MSNs.The release of IBU from the MSNs functionalized by Ca^2＋ cations is found to be effectively controlled when compared to the release from the MSNs without the functionalization of Ca^2＋ cations,which is due to the ionic interaction between carboxyl groups in IBU and Ca^2＋ cations in MSNs.