Ruthenium promotion of Co/SBA-15 catalysts with high cobalt loading for Fischer–Tropsch synthesis

30 wt.%Co/SBA-15 catalysts with different ruthenium contents (0.05–0.5 wt.%) were prepared by incipient wetness impregnation and characterized by diffuse reflectance infrared fourier transform spectroscopy, N₂ adsorption-desorption, X-ray diffractometry, temperature-programmed reduction and H₂ desorption, oxygen titration as well as X-ray photoelectron spectroscopy. The addition of a small amount of Ru promoter to Co/SBA-15 shifted the reduction temperature of both steps (Co₃O₄ → CoO and CoO → Co⁰) to lower temperatures and suppressed the formation of Co²⁺ species. After reduction, ruthenium atoms were encapsulated partially with cobalt cluster. There was no strong electronic interaction between metal cobalt and ruthenium, however, hydrogen spillover from ruthenium to cobalt oxide clusters occurred. With increasing ruthenium content, catalyst reducibility increased and the surface was enriched in cobalt atoms. Moreover, the peak intensities of both the linear and bridge types CO adsorption increased with the increase of ruthenium content, enhancing the catalytic activity on Fischer–Tropsch synthesis.     

Template synthesis and magnetic response of polyaniline/Fe3O4 composite microtubes

Template synthesis technique was employed to prepare magnetic polyaniline (PANI)/Fe₃O₄ composite microtubes using anodic aluminum oxide (AAO) membrane as template. Magnetic microtubes were obtained through in situ polymerization of aniline in the presence of Fe₃O₄ nanoparticles in the microchannels of template. A tubular structure was formed once when aniline was preferentially adsorbed and polymerized on the surface of channels wall. Electron microscope images demonstrated that the shape and size of guest (PANI/Fe₃O₄ composite microtubes) were strictly depended on those of the host (template channels). Magnetic force microscopy images showed that the PANI/Fe₃O₄ composite microtubes possessed reasonable magnetism and the magnetism distribution of microtubes was regular as distribution of template channels. Moreover, the magnetic response and oriented arrangement of PANI/Fe₃O₄ microtubes were fulfilled in the magnetic field. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of the molecular weight of poly(ether imide) on the viscoelastic phase separation of poly(ether imide)/epoxy blends

The phase separation of diglycidyl ether of bisphenol A/methyl tetrahydrophthalic anhydride blends modified with three poly(ether imide)s (PEIs) of different molecular weights was investigated with scanning electron microscopy (SEM) and time‐resolved light scattering (TRLS). The morphologies observed by SEM for the three blends were all close to a cocontinuous structure with different periodic distances. The results of TRLS indicated that the phase separation for the PEI‐modified epoxy blends took place according to the spinodal decomposition mechanism and the onset time of phase separation, with the periodicity of the phase structure depending on the PEI molecular weight and cure temperature. The time‐dependent peak scattering vector was simulated with a Maxwell‐type viscoelastic relaxation equation, indicating that the coarsening process of epoxy droplets was mainly controlled by the viscoelastic flow. Relaxation times obtained at different temperatures for the three blends could be described by the Williams–Landel–Ferry equation. The effects of the PEI molecular weight on the processes of viscoelastic phase separation were investigated, and the observed trends could be explained qualitatively through thermodynamic analysis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

N2‐filled hollow glass beads as novel gas carriers for microcellular polyethylene

N₂‐filled hollow glass beads (HGB) were first used as novel gas carriers to prepare microcellular polymers by compression molding. Dicumyl peroxide was acted as crosslink agent to control the produced microcellular structure of low density polyethylene (LDPE)/HGB. The effect of temperature, pressure and the content of gel on the embryo‐foaming, and final‐foaming structure are investigated. Scanning electronic microscopy shows that the average cell size of microcellular LDPE ranges from 0.1 to 10 μm, and the foam density is about 10⁹–10¹¹ cells/cm³. A clear correlation is established between preserving desirable micromorphologies of microcellular LDPE in different processing stage and tuning processing factors. The pertinent foaming mechanism of microcellular materials foamed with HGB is proposed. Because of the good mechanical strength, low density, weak water‐absorption, and excellent heat insulate ability, microcellular LDPE has great potential application in energy building materials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical and rheological properties of PP/SEBS/OMMT ternary composites

The microstructure and mechanical properties of polypropylene (PP)/OMMT binary nanocomposites and PP/styrene‐6‐(ethylene‐co‐butylenes)‐6‐styrene triblock copolymer (SEBS)/OMMT ternary nanocomposites were investigated using X‐ray diffraction (XRD), transmission electron microscopy (TEM), and rheology and electromechanical testing machine. The results show that the organoclay layers are mainly intercalated and partially exfoliated in the PP‐based nanocomposites. The additions of SEBS and OMMT have no significant effect on the crystallization behavior of PP. At the same time, it can be concluded that the polymer chains of PP and SEBS have intercalated into the organoclay layers and increase the gallery distance after blending process based on the analytical results from TEM, XRD, and rheology, which result in the form of a percolated nanostructure in the PP‐based nanocomposites. The results of mechanical properties show that SEBS filler greatly improve the notched impact strength of PP, but with the sacrifice of strength and stiffness. OMMT can improve the strength and stiffness of PP and slightly enhance the notched impact strength of PP/PP‐g‐MA. In comparison with neat PP, PP/OMMT, and PP/SEBS binary composites, notched impact toughness of the PP/SEBS/OMMT ternary composites significantly increase. Moreover, the stiffness and strength of PP/SEBS/OMMT ternary nanocomposites are slightly enhanced when compared with neat PP. It is believed that the synergistic effect of both SEBS elastomer and OMMT nanoparticles account for the balanced mechanical performance of the ternary nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Modified continuous carbon fiber‐reinforced poly(phthalazinone ether sulfone ketone) composites by blending polyetherimide and polyethersulfone

Poly(phthalazinone ether sulfone ketone) (PPESK) is a novel high performance thermoplastic with outstanding high temperature resistance and excellent mechanical properties and therefore, it is a very ideal candidate matrix for advanced composites. However, its high melting viscosity makes the melting process difficult. In this article, two well‐known high performance thermoplastics, polyetherimide (PEI) and polyethersulfone (PES) were introduced to PPESK in order to reduce the melting viscosity of PPESK and to improve the properties of composites. The effect of addition of PEI and PES on the resultant composites was studied. A series of unidirectional composites were made of PPESK and its PEI and PES blends as matrix and continuous carbon fiber (T700) as reinforcement. The solution prepregging method and hot‐press molding method were used in preparation of composites. The effects of polymer blends matrix on mechanical properties, interfacial adhesion, and fracture mode were studied by three points bending, interlaminar shearing, porosity, and scanning electron microscope test. The results show that the mechanical properties and interfacial adhesion increases, and the porosity decrease after blending PEI or PES in the matrix. Addition of PEI and PES to PPESK results in an obvious transition of fracture mode. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

pH值对硝酸铵水溶液临界爆炸温度的影响

研究了氯离子含量一定时pH值对硝酸铵水溶液临界爆温的影响。结果表明,氯离子质量分数为1．0×10^-4时,pH值越小,硝酸铵水溶液的临界爆温越低,且pH值与临界爆温值呈线性关系。本研究结果对硝酸铵的安全生产有重要的参考价值。     

超声检测中数字频谱应用的初步研究

作者采用超声检测计算机数字处理系统和频谱分析技术,利用超声检测中的有关信号,成功地对超声检测仪电路,换能器的频率特性及缺陷对声波的调制进行了初步研究。     

塑性聚合物方法制备的钛酸铋钠钾纤维及其流变学性能

用塑性聚合物方法制备了可塑性好的钛酸铋钠钾(0.2K0.5Bi0.5TiO3-0.8Na0.5Bi0.5TiO3,KNBT)泥料.研究球磨时间、黏结剂、分散剂以及 pH值对泥料流变性能的影响.获得流变性能最佳的泥料配方及制备工艺.通过挤制成型法成功制备了品质优良的KNBT纤维.结果表明:球磨时间为16h,黏结剂质量分数(下同)为1.22%,分散剂为0.4%,pH值为7时,泥料获得最佳流变性能.     

4，4’-联苯二甲酸的合成研究

研究了4,4’-联苯二甲酸的合成,以联苯为原料,经过氯甲基化、氯化、水解得到了目标化合物,总收率48％,产品纯度99．2％。