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  • Chlorine as an Indicator in the Controllable Preparation of Active Nano-Gold Catalyst
  • 更新时间:2014-04-10;信息类型:SCI论文
  • The controllable preparation of nano-gold catalyst maintains a challenge. Except the parameters have been revealed before, here we’d like to show that controllable preparation of active nano-gold catalyst can be achieved using chlorine as an indicator. By tracing the chlorine concentration in the washing step, a series of Au/Fe2O3 catalysts were prepared with co-precipitation method. The applying of these catalysts in CO oxidation and reductive nitrobenzene N-alkylation suggested the active catalysts were prepared from solutions containing ~2 ppm chlorine. The catalytic activity dropped dramatically if the chlorine concentration is >4–6 or <<1 ppm. Extensive characterizations revealed that the active catalyst was composed by nano-gold on the edge of Fe2O3 particle with 8.92 Au-Au coordination numbers. Although the real role of chlorine in the variation of catalyst structure and activity was still ambiguous, the current results should promote the controllable preparation of active nano-Au catalyst.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-10/166.html
  • Sonochemical formation of iron oxide nanoparticles in ionic liquids for magnetic liquid marble
  • 更新时间:2014-04-10;信息类型:SCI论文
  • Ionic liquids (ILs)-stabilized iron oxide (Fe2O3) nanoparticles were synthesized by the ultrasonic decomposition of iron carbonyl precursors in [EMIm][BF4] without any stabilizing or capping agents. The Fe2O3 nanoparticles were isolated and characterized by X-ray powder diffraction, transmission electron microscopy and susceptibility measurements. The physicochemical properties of ILs containing magnetic Fe2O3 nanoparticles (denoted as Fe2O3@[EMIm][BF4]), including surface properties, density, viscosity and stability, were investigated in detail and compared with that of [EMIm][BF4]. The Fe2O3@[EMIm][BF4] can be directly used as magnetic ionic liquid marble by coating with hydrophobic and unreactive polytetrafluoroethylene (PTFE), for which the effective surface tension was determined by the puddle height method. The resulting magnetic ionic liquid marble can be transported under external magnetic actuation, without detachment of magnetic particles from the marble surface that is usually observed in water marble.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-10/163.html
  • Ferric hydroxide supported gold subnano clusters or quantum dots: enhanced catalytic performance in chemoselective hydrogenation
  • 更新时间:2014-04-09;信息类型:SCI论文
  • An attempt to prepare ferric hydroxide supported Au subnano clusters via modified co-precipitation without any calcination was made. High resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) have been employed to study the structure and chemical states of these catalysts. No Au species could be observed in the HRTEM image nor from the XRD pattern, suggesting that the sizes of the Au species in and on the ferric hydroxide support were less than or around 1 nm. Chemoselective hydrogenation of aromatic nitro compounds and a,b-unsaturated aldehydes was selected as a probe reaction to examine the catalytic properties of this catalyst. Under the same reaction conditions, such as 100 ◦C and1MPaH2 in the hydrogenation of aromatic nitro compounds, a 96–99% conversion (except for 4-nitrobenzonitrile) with 99% selectivity was obtained over the ferric hydroxide supported Au catalyst, and the TOF values were 2–6 times higher than that of the corresponding ferric oxide supported catalyst with 3–5 nm size Au particles. For further evaluation of this Au catalyst in the hydrogenation of citral and cinnamaldehyde, selectivity towards unsaturated alcohols was 2–20 times higher than that of the corresponding ferric oxide Au catalyst.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-09/109.html
  • Abnormal FT-IR and FTRaman spectra of ionic liquids confined in nano-porous silica gel
  • 更新时间:2014-04-06;信息类型:SCI论文
  • A new concept of designing and synthesizing highly dispersed ionic liquids was developed through physical confinement or encapsulation of them into silica gel matrix with sol–gel process. A series of silica gel confined ionic liquids were synthesized through this process and characterized by diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS) and FTRaman analysis, and abnormal FT-IR and FTRaman spectra were observed. The silica gel matrixes confined ionic liquid BMImBF4 were further characterized by BET analysis after the ionic liquid was almost completely washed out by acetone under refluxing conditions and meso-porous silica gel matrixes were obtained according to the N2 adsorption measurements, which suggested that the particle-size of the dispersed ionic liquids was in nano-scale. In consideration of the results obtained together, it could be found that the abnormal FT-IR and FTRaman spectra were changed with the poresize of the silica gel matrix. For example, obvious abnormal FT-IR and FTRaman spectra appeared when the particle-size of ionic liquid BMImBF4 is smaller than 11 nm while they disappeared again if the corresponding particle-size >11 nm. These results indicated that nano-effect, or restriction effect, produced from the nano-pores of silica gel was the reason for the abnormal FT-IR and FTRaman spectra.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-06/36.html
  • 化学所等用离子液体水凝胶一步合成负载型纳米催化材料
  • 更新时间:2014-03-26;信息类型:国内研究进展
  • 中国科学院化学研究所胶体、界面与化学热力学实验室与中科院高能物理研究所同步辐射实验室合作研究 发现,无机盐可以诱导离子液体形成热力学稳定的水凝胶,并且可以制备多孔离子液体水凝胶。在此基础上,他们提出了利用离子液体多孔水凝胶一步合成负载型金 属纳米催化材料的方法。这种方法具有普适性好、绿色环保、操作简单等优点,体载体可以是无机材料、有机高分子材料、有机无机杂化材料等。利用此方法制备的 催化剂具有金属纳米粒子尺寸小、尺寸分布很窄、载体具有多级孔结构等特点。制备的Au/SiO2、Ru/SiO2、Pd/Cu-MOF分别对苯甲醇氧化酯化反应、苯加氢反应、苯甲醇氧化反应具有极高的催化活性、选择性和稳定性,并且容易重复使用。这一新颖方法在高效负载型纳米催化材料制备方面具有良好的应用前景。相关成果发表在近期的《美国化学会志》(J. Am. Chem. Soc., 2014, 136, 3768-3771)上。
  • 链接地址:http://www.ionicliquid.org/research/2014-04-24/164.html
  • KooBoos专家访谈:抗污染应首选纳米技术
  • 更新时间:2014-02-21;信息类型:商品广告
  • 在纳米科技发展史上,纳米抗菌离子液体中的生物催化反应是离子液体在催化领域最激动人心的发展,其最引人注目的成就如人造甜味剂酶催化的合成。KooBoos抗菌系列产品上市前,广东纳米材料工程中心早已将此纳米长效抗菌技术用于冰箱,空调,及广泛使用于高端汽车出厂前的车内地毯饰件等抗菌处理。
  • 链接地址:http://www.ionicliquid.org/research/2014-04-25/235.html