胺功能化的拟薄水铝石纳米颗粒负载的Mn-V复合物:高效的烯烃环氧化催化剂（英文）

将具有高比表面积和表面高度羟基化的拟薄水铝石纳米颗粒与3-(3甲氧基硅烷)-正丙胺进行共价结合而官能团化,再用于负载硫酸氧钒和六羰基钼络合物。所得样品采用红外光谱、粉末X射线衍射、热重-差热分析、X射线光电子能谱、元素分析、电感耦合等离子体和透射电镜等技术进行了表征,并用于顺-环辛烯的环氧化反应中,优化了诸如溶剂和氧化剂等反应条件.反应过程采用气-液色谱进行监测.重复使用实验表明,该纳米催化剂可重复使用多次,并保持顺-环辛烯接近完全环氧化.所得到的优化反应条件也成功用于其它的取代烯烃的环氧化反应中.     

金-硅胶催化剂的一步合成及其催化苯乙烯环氧化性能的研究

环氧苯乙烷具有重要的经济价值,现有的工业生产技术存在能耗高及环境污染大等诸多问题,使得环境友好的苯乙烯环氧化生产工艺的开发具有重要意义.采用一步合成法制备了系列金-硅胶纳米球催化剂,实现了纳米金的高度分散(粒径6.4 nm),对苯乙烯环氧化反应表现出较好的催化活性及产物选择性.通过X射线粉末衍射、红外光谱及X射线光电子能谱等表征技术,结合苯乙烯环氧化反应性能的考察,对金-硅胶催化剂的制备条件进行了优化.     

中孔MCM-41负载Ru纳米粒子催化剂用于超声辐射下芳烃选择氧化反应

以中孔MCM-41为载体制得均一分散的粒径约5nm的Ru纳米粒子催化剂MCM-41-Ru,采用电感耦合等离子体、透射电镜、能量散射谱、X射线衍射和N2吸附-脱附法对其进行了表征,并将其作为可重复使用高效催化剂用于超声辅助芳烃选择氧化反应.结果表明,在超声辐射和KBrO3为氧化剂条件下,MCM-41-Ru催化剂加速了氧化反应,并以较高产率得到目的产物.回收的催化剂用于下次反应时活性保持不变,但其活性中心性质发生变化.     

中孔MCM-41负载Ru纳米粒子催化剂用于超声辐射下芳烃选择氧化反应（英文）

以中孔MCM-41为载体制得均一分散的粒径约5 nm的Ru纳米粒子催化剂MCM-41-Ru,采用电感耦合等离子体、透射电镜、能量散射谱、X射线衍射和N_2吸附-脱附法对其进行了表征,并将其作为可重复使用高效催化剂用于超声辅助芳烃选择氧化反应.结果表明,在超声辐射和KBrO_3为氧化剂条件下,MCM-41-Ru催化剂加速了氧化反应,并以较高产率得到目的产物.回收的催化剂用于下次反应时活性保持不变,但其活性中心性质发生变化.     

纳米SnO2高效催化烯烃与H2O2环氧化反应研究

构建了用于催化烯烃与过氧化氢环氧化反应的高效、 绿色催化反应体系. 首先, 通过水热合成法制备了纳米SnO₂, 并在320 ℃下煅烧. 随后, 对所有催化剂进行X射线衍射(XRD)、 紫外-可见漫反射光谱(UV-Vis)、 傅里叶变换红外光谱(FTIR)、 扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征. 进一步将催化剂用于以H₂O₂水溶液为氧化剂环氧化各种官能化烯烃(包括环烯烃, 苯乙烯和直链烯烃)的反应, 以高转化率和高选择性得到了环氧化物. 在相似的反应条件下, 发现合成的纳米SnO₂-170催化剂在催化1-甲基环己烯与H₂O₂的环氧化反应中的活性最佳, 在2 h内1-甲基环己烯的转化率达到100%, 环氧化物选择性达到100%.     

顺, 顺-1,5-环辛二烯的单重态氧反应及其产物的重排

本文报道用竹红菌甲素作光敏剂匹配高压钠灯光源, 对1,5-环辛二烯(1)进行单重态氧氧化反应, 高产率和立体选择性地得到顺-5,8-二(氢过氧基)-1,3-环辛二烯(7). 证明了7还原产物顺-5,8-二烃基-1,3-环辛二烯(8)热重排的产物是6-羟基-4-环辛烯酮(3). 而不是6-羟基-3-环辛烯酮(6). 并讨论了热重排过程的机理.     

Y型分子筛固载Co(Salprn)配合物的制备及催化烯烃环氧化性能

采用自由配体法将双水杨醛缩丙二胺席夫碱钴配合物Co(Salprn)封装于Y型分子筛超笼中,并通过X射线衍射、漫反射UV-Vis光谱、FT-IR光谱和差热分析技术对所制备的催化剂进行了表征。该催化剂样品( [Co(Salprn)]-Y)在苯乙烯环氧化反应中较纯配合物Co(Salprn)表现出很高的催化活性。反应条件（包括溶剂、催化剂用量、异丁醛浓度和反应时间）对催化性能有较大影响。研究结果还表明,[Co(Salprn)]-Y对其他烯烃的环氧化也具有较高催化活性。其活性顺序为苯乙烯﹥环己烯﹥环辛烯﹥正辛烯。     

从三聚氰胺制得工业用深度脱硫的绿色纳米催化剂PMoV/Fe3O4/g-C3N4: 合成与表征

采用简便的化学浸渍法制备了新型磁性可分离的纳米复合物H5PMo10V2O40/Fe3O4/g-C3N4(PMoV/Fe3O4/g-C3N4),并进行了详细的表征,采用电位滴定法测定了催化剂酸性.该PMoV/Fe3O4/g-C3N4纳米复合物在硫化物选择氧化为砜或亚砜的反应中表现出较高的催化活性;考察了在优化反应条件下,它在含硫(包括二苯并噻吩DBT)模拟油或真实石油的催化氧化反应中的催化性能;特别考察了各种含氮化合物,以及1-环和2-环芳香烃作为共溶剂对DBT脱硫效果的影响.采用外加磁场即可方便地将该催化剂从反应混合物中分离和回收.选取最好的萃取剂,通过简单的倾滤就可很容易地将剩余反应物从产物中分离出来.该纳米催化剂具有高催化活性,且容易重复使用,至少可以重复使用4次而未见催化活性明显下降.     

自发氧化还原法制备Co3O4/CeO2纳米复合材料及其CO催化氧化反应结构优化

采用简单的自发氧化还原法合成了Co3O4/CeO2纳米复合材料,采用透射电子显微镜(TEM)\,X射线衍射(XRD)及X射线光电子能谱(XPS)等分析手段对样品进行了表征,并探究了反应参数对其催化CO氧化反应活性的影响.结果表明,Co/Ce摩尔比、pH值、反应温度和煅烧温度均显著影响Co3O4/CeO2纳米复合材料的催化性能;性能最优的样品用于催化CO氧化反应在140℃时即可实现100%的转化率,并且在循环测试中其催化活性保持不变,显示出良好的稳定性.     

间苯二酚保护的抗菌Pd纳米粒子催化C-C偶联反应活性(英文)

合成了新型四甲氧基间苯二酚-四酰肼(TMRTH),并作为还原剂和封端剂用于合成水分散性稳定的Pd纳米粒子(PdNPs).采用紫外-可见光谱、透射电镜、能量散射谱和粉末X射线衍射对所得TMRTH-PdNPs样品进行了表征.结果表明,所制纳米粒子具有多分散性,粒径为5±2 nm,并在Suzuki-Miyuara交叉偶联反应中可重复使用5次,具有较高的催化效率.该纳米催化剂在反应时间、催化剂用量和可重复使用性能等方面优于常规Pd催化剂.另外,TMRTH-PdNPs样品对革兰(氏)阳性菌具有较好的抗菌活性,因而有望用于一些生物领域.     

Preparation and characterization of Fe3O4@Boehmite core‐shell nanoparticles to support molybdenum or vanadium complexes for catalytic epoxidation of alkenes

Fe₃O₄ core nanoparticles were prepared via a solvothermal process, and then they were covered with a surface hydroxyl‐rich boehmite shell via the hydrothermal‐assisted sol–gel processing of aluminum 2‐propoxide. The outer surface of the boehmite shell was subsequently covalently functionalized with 3‐(tri‐methoxysilyl)‐propylamine or 3‐(tri‐methoxysilyl)‐propyl chloride, and the terminal chlorine groups were treated with imidazole. These compounds were used to support the hexa‐carbonyl molybdenum and oxo‐sulfato vanadium (IV) complexes. The supported catalysts were characterized by the FT‐IR, CHN, ICP, and TEM analysis techniques. They were then used in the epoxidation of cis‐cyclooctene. The catalytic procedures were optimized for different parameters such as the solvent, oxidant, and temperature. The reaction progress was investigated by the gas–liquid chromatography analysis. The catalysts used were simply recovered from the solution by applying a magnet, and recycling the experiments revealed that the heterogeneous nanocatalysts could be repeatedly used for the epoxidation of cis‐cyclooctene. The optimized conditions were also successfully used for the epoxidation of some other alkenes.     

The Unexpected Role of SeVI Species in Epoxidations with Benzeneseleninic Acid and Hydrogen Peroxide

Benzeneperoxyseleninic acid has been proposed as the key intermediate in the widely used epoxidation of alkenes with benzeneseleninic acid and hydrogen peroxide. However, it reacts sluggishly with cyclooctene and instead rapidly decomposes in solution to a mixed selenonium–selenonate salt that was identified by X‐ray absorption and ⁷⁷Se NMR spectroscopy, as well as by single crystal X‐ray diffraction. This process includes a selenoxide elimination of the peroxyseleninic acid with liberation of oxygen and additional redox steps. The salt is relatively stable in the solid state, but generates the corresponding selenonic acid in the presence of hydrogen peroxide. The selenonic acid is inert towards cyclooctene on its own; however, rapid epoxidation occurs when hydrogen peroxide is added. This shows that the selenonic acid must first be activated through further oxidation, presumably to the heretofore unknown benzeneperoxyselenonic acid. The latter is the principal oxidant in this epoxidation.     

Boehmite nano‐particles functionalized with silylpropylamine‐supported Keggin‐type heteropolyacids: Catalysts for epoxidation of alkenes

Boehmite nano‐particles with a high degree of surface hydroxyl groups were covalently functionalized by 3‐(trimethoxysilyl)‐propylamine to support H₃[PMo₁₂O₄₀], H₃[PW₁₂O₄₀], H₄[SiMo₁₂O₄₀] and H₄[SiW₁₂O₄₀] Keggin‐type heteropolyacids. After characterization of these catalysts by FT‐IR, powder X‐ray diffraction, TG/differential thermal analysis, CHN, inductively coupled plasma and transmission electron microscopy techniques, they were applied to the epoxidation of cis‐cycloocten. The progress of the reactions was investigated by gas–liquid chromatography, and the catalytic procedures were optimized for the parameters involved, such as the solvent and oxidant. The results showed that 25 mg of supported H₃[PMo₁₂O₄₀] catalyst in 1 ml C₂H₄Cl₂ with 0.5 mmol cyclooctene and 1 mmol tert‐butylhydroperoxide at reflux temperature gave 98% yield over 15 min. Recycling experiments revealed that these nanocatalysts could be repeatedly applied up to five times for a nearly complete epoxidation of cis‐cycloocten. The optimized experimental conditions were also used successfully for the epoxidation of some other alkenes, such as cyclohexene, styrene and α‐methyl styrene.     

Schiff base‐functionalized boehmite nanoparticle‐supported molybdenum and vanadium complexes: efficient catalysts for the epoxidation of alkenes

Boehmite nanoparticles, with high surface area and high degree of surface hydroxyl groups, were prepared via hydrothermal‐assisted sol–gel processing of aluminium 2‐butoxide. The produced powder was covalently functionalized with 3‐(trimethoxysilyl)propylamine, and then, in order to support vanadium oxosulfate and molybdenum hexacarbonyl complexes, all the terminal amine groups were changed to Schiff bases by refluxing with salicylaldehyde. These catalysts were applied in the epoxidation of cis‐cyclooctene and other olefins with tert‐BuOOH in CCl₄. The catalytic procedures for both catalysts were optimized for various parameters such as solvent and oxidant. Recycling experiments revealed that these heterogeneous nano‐catalysts could be repeatedly applied for the epoxidation of alkenes. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis,characterization and catalytic application of a new organometallic oligomer based on polyhedral oligomeric silsesquioxane

Although homogeneous catalysts provide high performance and selectivity, the difficulty of separation and recycling of these catalysts has bothered the scientific community worldwide. Therefore, the demand for heterogeneous catalysts that possess the advantages of homogeneous ones, with ease of separation and recyclability remains a topic of major impact. The oligomeric catalyst synthesized in this work was characterized using elemental analysis, Fourier transform infrared, ¹³C NMR, ²⁹Si NMR and energy‐dispersive X‐ray spectroscopies, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy and Brunauer–Emmett–Teller analysis and compared to its homogeneous counterpart [W(CO)₃Br₂(ATC)] in the epoxidation of 1‐octene, cyclooctene, (S )‐limonene, cis ‐3‐hexen‐1‐ol, trans ‐3‐hexen‐1‐ol and styrene. The results showed that the percentage conversion for the homogeneous species [W(CO)₃Br₂(ATC)] was slightly higher than for the oligomeric catalyst (POSS‐ATC‐[W(CO)₃Br₂]). Furthermore, the selectivity for epoxide of the oligomeric catalyst was greater than that of the homogeneous catalyst by about 25% when (S )‐limonene was used. Great conversions (yields) of products were obtained with a wide range of substrates and the catalyst was recycled many times without any substantial loss of its catalytic activity.     

Enhanced epoxidation of soybean oil by novel Al2O3–ZrO2–TiO2 solid acid catalyst

This study aims to develop highly efficient, recyclable solid catalysts for the epoxidation of vegetable oils. An Al₂O₃–ZrO₂–TiO₂ solid acid catalyst was prepared by a co‐precipitation/impregnation method and characterised through scanning electron microscopy, energy‐dispersive spectroscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, Fourier‐transform infrared and nitrogen adsorption–desorption analyses. The solid acid catalyst with a high surface area and typical slit pore adsorption was successfully synthesised. Al₂O₃–ZrO₂–TiO₂ also exhibits high stability and improved catalytic efficiency in the epoxidation of soybean oil. An oil conversion rate of 86.6%, which is higher than that of conventional catalysts, was obtained with a catalyst loading of 0.8 wt% and was maintained at 76.6% even after recycling the catalyst three times. The performance of the solid catalyst was slightly superior to that of H₂SO₄. Therefore, this novel catalyst may potentially be applicable in catalysing soybean oil epoxidation.     

Polymeric Heterogeneous Catalysts of Transition‐Metal Oxides: Surface Characterization,Physicomechanical Properties,and Catalytic Activity

We investigate the physicomechanical properties of polymeric heterogeneous catalysts of transition‐metal oxides, specifically, the specific surface area, elongation at break, breaking strength, specific electrical resistance, and volume resistivity. Digital microscopy, Fourier‐transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and energy‐dispersive analysis are used to study the surfaces of the catalysts. The experimental results show that polymeric heterogeneous catalysts of transition‐metal oxides exhibit high stability and can maintain their catalytic activity under extreme reaction conditions for long‐term use. The oxidation mechanism of sulfur‐containing compounds in the presence of polymeric heterogeneous catalysts of transition‐metal oxides is confirmed. Microstructural characterization of the catalysts is performed by using X‐ray computed tomography. The activity of various catalysts in the oxidation of sulfur‐containing compounds is determined. We demonstrate the potential application of polymeric heterogeneous catalysts of transition‐metal oxides in industrial wastewater treatment.     

埃洛石表面修饰并负载salen钼高效催化烯烃环氧化反应

采用温和的化学表面改性和自组装方法成功制备了埃洛石纳米管负载salen钼(HNTs-SL-Mo)催化剂,运用透射电镜、X射线衍射、红外光谱、诱导偶合等离子体谱和X射线光电子能谱表征了催化剂的形态、大小和分散性等性质。结果证明了salen结构的存在和埃洛石配位钼催化剂的成功制备。制备的催化剂在各种烯烃的环氧化反应中均有很好的活性,且活性高于均相催化剂。对比实验表明,在固定MoO(O2)2(DMF)2时, salen结构发挥了重要作用,不能用N原子作为单一配体来代替。本文还推测了钼和salen配体可能的连接方式和该催化剂催化烯烃环氧化反应的机理。该催化剂在重复使用8次后其活性未见明显下降,表现出优异的重复使用性能。由于埃洛石是一种廉价易得的材料,因此它可为设计效果独特的催化剂提供一个选择。     

Excellent alkene epoxidation catalytic activity of macrocyclic‐based complex of dioxo‐Mo(VI) on supermagnetic separable nanocatalyst

A phenoxybutane‐based Schiff base complex of cis‐dioxo‐Mo(VI) was supported on paramagnetic nanoparticles and characterized using powder X‐ray diffraction, infrared, diffuse reflectance and atomic absorption spectroscopies, scanning and transmission electron microscopies and vibrating sample magnetometry. The separable nanocatalyst was tested for the selective epoxidation of cyclohexene, cyclooctene, styrene, indene, α‐pinene, 1‐octene, 1‐heptene, 1‐dodecene and trans‐stilbene using tert‐butyl hydroperoxide (80% in di‐tert‐butyl peroxide–water, 3:2) as oxidant in chloroform. The catalyst was efficient for oxidation of cyclooctene with 100% selectivity for epoxidation with 98% conversion in 10 min. We were able to separate magnetically the nanocatalyst using an external magnetic field and used the catalyst at least six successive times without significant decrease in conversion. The turnover frequency of the catalyst was remarkable (2556 h^?1 for cyclooctene). The proposed nanomagnetic catalyst has advantages in terms of catalytic activity, selectivity, catalytic reaction time and reusability by easy separation.     

Au/ZrLa掺杂 CeO2催化剂在CO氧化反应中优异的催化活性：锆镧协同作用

在过去的25年,纳米金催化剂上 CO氧化反应得到广泛研究,但始终没有一致的结论。这是因为影响纳米金催化活性的因素很多,包括金的价态、载体的性质、氧空位、金属与载体之间的相互作用等,尤其是各影响因素之间相互牵制,增加了催化反应机理的研究难度。氧化铈载体表面氧缺陷的浓度较高,有利于活性金属组分在其表面的稳定和分散,因此氧化铈纳米晶负载的 Au催化剂受到广泛关注。此外,当 CeO2晶格中部分 Ce被化学性质不同的其它元素取代后,可以促进 CeO2晶格氧的活化,提高氧的储放能力,从而有利于催化反应进行。因此,本文采用水热法合成了组成均匀的 CeO2, CeZrOx和 CeZrLaOx三个载体,并通过沉淀-沉积法负载金。利用 X射线衍射(XRD)、拉曼光谱(Raman)、X射线光电子能谱(XPS)、高分辨透射电镜(HRTEM)、X射线吸收精细结构(XAFS)和氢气程序升温还原(H2-TPR)等技术分析了催化剂的物相结构、表面性质、形貌以及金纳米颗粒的大小和价态等性质,并结合其在 CO氧化反应中催化性能的差异,探讨影响金催化剂活性的关键因素。 XRD, TEM, HRTEM和 XAFS结果表明,三个载体上所得金纳米颗粒的平均尺寸都在2–4 nm,且分散较好; XPS结果表明,影响催化剂活性的关键因素不是金的价态,而是载体表面的活性氧物种。从Raman结果可知,掺杂后的氧化铈载体上氧空位浓度明显增加,因而催化剂活性都有所提高。 H2-TPR进一步探讨了三个载体以及负载金后其氧化还原能力的变化,结果表明,金和载体之间的相互作用可以增强载体的氧化还原性能以及表面氧空位浓度,进一步提高了催化剂活性,而负载金催化剂氧化还原性能的变化与载体的组成密切相关。由于锆的掺杂可使金与载体之间相互作用减弱,而镧则增强了二者间相互作用,因此 Au/CeZrLaOx催化剂上锆和镧的协同掺杂作用使其表面活性氧物种浓度最高,低温时表现出最高的催化活性。