Ethylene polymerization with novel silicon bridged homo-dinuclear cyanoethyl cyclopentadienyl

Novel homo-dinuclear silicon bridged cyanoethyl cyclopentadienyl complexes of titanium and zirconium (CH3)2Si((η5-C5H3CH2CH2CN)(C5H5)MCl2)2 (M=Ti(1), Zr(2)) were synthesized and developed for the polymerization of ethylene. Compared with their corresponding mononuclear complexes (η5-C5H4CH2CH2CN)(C5H5)MCl2 (M=Ti(3), Zr(4)), the dinuclear complexes had higher catalytic activity. And the polyethylene produced had a higher molecular weight than that obtained with mononuclear catalysts. Effects of conditions on the ethylene polymerization catalyzed by (2)/MAO (methylaluminoxane) were studied in detail. The catalyst showed a very high activity ( >106g PE/mol Zr*h) under low catalyst concentration and high molar ratio of Al/Zr.     

Chemically processed Nb-doped SrTiO3 films and properties

Homogeneous, crack-free SrNb_xTi_1−x O₃ thin films on (110) silicon substrates were successfully fabricated by sol-gel processing. The optimum route and conditions were systematically investigated. Sr(OAc)₂ glacial acctic acid solution, after being refluxed and reacted with tartrate, formed Sr(OAc)₂(C₄H₆O₆)₂; Ti(OBu)₄ formed Ti(OAc)_4−x (AcAc)_x after having the ligand partially exchanged with AcAc, while Nb(OC₂H₅)₅ formed (OAc)₂Nb(AcAc) (C₄H₆O₆) by exchanging of ligand in glacial acetic acid with (CH₃CO)₂O. All the metal species after undergoing partial hydrolysis and polymerization with hydroxyl or oxygen, formed SrNb_xTi_1−x O₁₃ cluster sol. Methyl cellulose (MCL) caused SrNb_xTi_1−x O₃ sol to have polymeric structure and easily form films. SrNb_xTi_1−x O₃ films with perovskite were subsequently formed after being annealed at 650∼750 °C for 60 min in 25% N₂+75% H₂ (volume ratio) atmosphere. Resistivity of the SrNb_0.1Ti_0.9O₃ films at room temperature was 64 μω·cm, a particular T ² temperature dependence of the resistivity, from 25 K up to room temperature, was observed. Project (No. 2002CB613305) supported by the National Basic Research Program (973) of China     

Vapor-liquid equilibrium simulation of binary and ternary mixtures of CH4, C2H4 and iso-C4H10

The vapor-liquid equilibrium（VLE） properties for the binary and ternary mixtures of CH4,C2H4 and isoC4H10 are of great importance in the recovery of ethylene from mixture containing CH4 and C2H4 with iso-C4H10 as solvent.Hence,Gibbs ensemble Monte Carlo（GEMC） simulations were used to estimate vapor-liquid equilibrium for the binary and ternary mixtures of CH4,C2H4 and iso-C4H10 with the united atom potential NERD model.The selected simulation conditions are based on the experiment in the literature.The results of this work were shown to be in satisfactory agreement with available experimental data and predictions of Peng-Robinson equation of state.The structure of simulated liquid phase is also characterized by radial distribution function（RDF）,which contributes to further understanding of the VLE curve of these systems.RDF is not sensitive to the pressure and temperature range.With the increase of pressure or the decrease of temperature,the molecules tend to gather together.     

Polymerization of methyl methacrylate with ethylene bridged heterodinuclear metallocene of samarium and titanium-study on synergism and kinetics

Comparison of MMA polymerization results with samarocene chloride, titanocene chloride and the title heterodinuclear (Sm−Ti) catalyst, respectively, showed synergism in the Sm-Ligand-Ti system, which obviously influenced the polymerization behaviors, for example, of yeilding higher activity and higher molecular weight polymer. Kinetic studies on polymerization of MMA with ethylene bridged samarocene and titanocene chloride/Al(i-Bu)₃ showed that the polymerization rate was first-order on the catalyst concentration, and 1.9-order on the monomer. The overall activation energy measured was 52.8 kJ/mol. Project supported by NSFC (No. 20074028), and SINOPEC(X598037).     

Preparation and gas sensitive properties of nanometer-sized SnO2

Nanometer-sized SnO₂ particles were prepared by a sol-gel method using inorganic salt as a precursor material. Its crystallization was investigated by means of TG-DTA, IR absorption spectra, X-ray diffractometry and TEM as well as its resistivity change and the gas sensitivity varied with temperature were measured in various reducing gas. The results indicate that well-crystallized nano-sized SnO₂ with size around 15nm can be obtained at annealing temperature 600°C. The activation energy for the growth of nano-SnO₂ was calculated to be 26. 55kJ. mol⁻¹ when the annealing temperature was higher than 500°C. The measurements also show that there is a peculiar resistance change varied with temperature for nano-SnO₂. It has relevance to the increase in surface adsorbed oxygen. The selective detectivities to C₄H₁₀ and petrol can be increased when ruthenium ion was doped in nano-SnO₂ as a catalyst and so do the gas sensitivity to CO, CH₄, H₂ etc. when rhodium ion was doped in. The detection to the several reducing gas can be realized when the temperature ranged from 260°C to 400°C.     

Applications of water sensitivity in situ remediation at saltwater-freshwater interface

Based on the laboratory experiments with the saltwater and freshwater replacing each other in the level sand column, taking the kaolin, illite, smectite, bivalent hydrargyrum ion (Hg²⁺) and phenol (C₆H₅OH) as examples, this paper studies the applications of water sensitivity in situ remediation in saltwater-freshwater transition zone. In the water sensitivity process, the release and migration of clay minerals can make the hydraulic conductivity (HC) decrease and pollutants remove. A new type of low penetrable or impenetrable purdah can be built by adding clay minerals into the sand media to replace the underground concrete impenetrable wall to prevent seawater intrusion, and a number of the heavy metals and organic pollutants in the sand media can be removed by in situ remediation. The results show that the content of kaolin and illite influences the water sensitivity process slightly, and HC of the sand columns descends from 0.011 cm/s to 0.001 4 cm/s and 0.001 2 cm/s respectively even if the content reaches 12% (weight ratio, sic passim). However, for smectite, HC descends sharply to about 1×10⁻⁸ cm/s when its content reaches 4%, and no water can flow through the sand columns beyond 5%. The particle release and migration processes can remove the Hg²⁺ and C₆H₅OH out of the sand columns efficiently, the removing rate of Hg²⁺ is 31.68% when the freshwater and saltwater are filtered through the sand columns polluted by Hg²⁺, while it is 67.55% when the water sensitivity occurs. With the same method, the removing rates of C₆H₅OH under the fluid flow and water sensitivity are 55.71% and 43.43% respectively. Supported by National Natural Science Foundation of China (No. 40572142). HAN Zhiyong, born in 1976, male, Dr, associate Prof.     

柠檬酸含量对溶胶凝胶自燃烧法制备的钡铁氧体磁性能的影响

BaFe12O19 powders with nanocrystaUine sizes were produced by sol-gel auto-combustion method. The precursors were prepared under the molar ratios of citric acid to the metal nitrate of 0.5, 1.0 and 1.5. Appropriate ethylene diamine （C2H8N2） was added in order to adjust pH of 7. The ions distribution of citric acid at different pH explains the effect of citric acid in the starting solution. The XRD patterns of the as-burnt powders and annealing powders show different phases for different citric acid content. In addition, the lattice constants （a, c） derived from X-ray diffraction pattern were changed from 0.58881 nm to 0.58997 nm and 2.32057 nm to 2.32296 nm respectively. The data from VSM indicated that the powder with high citric acid content took on good magnetic properties. Pure single BaFe12O19 of the specific maximum magnetization M（1 T）≈ 49.73 Am^2/kg, the specific remanent magnetization Mr ≈ 30.77 Am^2/kg and the coercive force He≈ 467 kA/m was produced when the molar ratios of citric acid to the metal nitrate was 1.5.     

Preparation of SO4^2-/TiO2-La2O3 solid superacid and its catalytic activities in acetalation and ketalation

SO4^2- / TiO2-La2O3, a novel solid superacid, was prepared and its catalytic activities at different synthetic conditions are discussed with esterification of n-butanoic acid and n-butyl alcohol as probing reaction. The optimum conditions have also been found, mole ratio of n（La^3＋）：n（Ti^4＋） is 1：34, the soaked consistency of H2SO4 is 0.8 tool/L, the soaked time of HESO4 is 24 h, the calcining temperature is 480 ℃, the calcining time is 3 h. Then it was applied in the catalytic synthesis often important ketals and acetals as catalyst and revealed high catalytic activity. Under these conditions on which the molar ratio of aldehyde/ketone to glycol is l： 1.5, the mass ratio of the catalyst used in the reactants is 0.5%, and the reaction time is 1.0 h, the yields of ketals and acetals can reach 41.4%-95.8%.     

Optimization of Co-precipitation Condition for Preparing Molybdenum-Based Sulfur-Resistant Methanation Catalysts

In this study, the effects of ZrO_2 carrier precursors, MoO_3 loading, and washing treatment on the catalytic performance of Mo O_3/ZrO_2 toward sulfur-resistant methanation were investigated. All the catalysts were prepared by co-precipitation method and further characterized by N_2 adsorption–desorption, H_2-temperature-programmed reduction, X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The prepared MoO_3/ZrO_2 catalysts were tested in a continuous-flow pressurized fixed bed reactor for CO methanation. The results revealed that the carrier precursors, MoO_3 loading, and washing treatment affected not only the crystalline phase of Mo species but also the grain size of ZrO_2 carrier and consequently influenced the MoO_3/ZrO_2 activity toward sulfur-resistant methanation. The 25 wt% MoO_3/ZrO_2 catalyst prepared using Zr(NO_3) 4 ·5 H_2O as the precursor and treated by water washing displayed the best activity for sulfur-resistant methanation due to its greater number of octahedral Mo species and smaller ZrO_2 grain size.     

Partially reversible photochromic behavior of organic-inorganic perovskites with copper（Ⅱ） chloride

We report that the ultraviolet （UV） light induced photochromic behavior of layered organic-inorganic perovskite material of （C4H9NH3）2CuCl4, changed from yellow to brown after irradiation with UV light （10 mW/cm^2） and partially recovered through storage in the dark. （C4H9NH3）2CuCl4 exhibited two distinct absorption bands centered at 286 nm （band Ⅰ） and 384 nm （band Ⅱ）, which were attributed to the photo-induced exciton formed in 2D inorganic layers sandwiched by organic layers. The blue shift of band Ⅰ from 287 to 269 nm as well as the decrease of the intensity of band Ⅰ and band Ⅱ could be found when samples were irradiated under UV light for different length of time. The simultaneous weakening of the intensity of the N-H...Cl hydrogen bond as well as the vibration of the long Cu-Cl bond in the distorted CuCl6^4- octahedron could be detected from the Fourier transform infrared （FTIR） spectra, which resulted the change of charge distribution of the dissymmetric Cl-Cu...Cl bond and the resulting photochromic behavior.     

Synthesis of Novel Ionic Liquid （[C4CNmim]^＋PF6^-） and Application to Preparation of Polyketone

N-valeronitrile-N’-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR and 1 H NMR.As a medium,the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St).Some synthetic conditions were determined,including the usage of ionic liquid,palladium composite catalyst and methanol,CO pressure,reaction time and reaction temperature.The influence of these factors on catalytic activity was analyzed.The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition:composite catalyst 0.015 mmol,ionic liquid 3 mL,methanol 0.75 mL,CO pressure 2MPa,reaction time 2 h and reaction temperature 70℃.This CO/St copolymerization within [C 4 CNmim]+ PF 6 system could facilitate ionic liquids with efficient and economical applications to polymeric materials.     

The polymerization of methyl methacrylate with a new Tin-bridged yttrocene/Al(I-Bu)3

A new catalyst composed of Tin-bridged yttrocene Ph₂Sn(MeCp)₂YCI (MeCp=methylcyclopentadienyl) and Al (i-Bu)₃ was successfully developed for the polymerization of methyl methacrylate (MMA). Detailed study of factors (such as the molar ratio of Al/Cat., catalyst concentration, various solvents, temperature and time) influencing polymerization reaction indicated that the catalytic active species may be still somewhat stable at high temperature and still have a long catalytic lifetime.¹H NMR spectrum showed about 65% syndiotactic content in the polymethyl methacrylate (PMMA) prepared. From kinetic studies, the polymerization rate equation may be expressed as Rp=Kp[Cat.]^2.4. The overall activation energy of polymerization is 20.9±3.1 kJ/mol. Project(29774021) supported by the Natural Science Foundation of China and National Laboratory of Element-Organic Chemistry, Nakai, University.     

茂金属配合物{o-[OPh(CO2)(R)]Zr(G5H4SiMe3)2} (R:NO2,CN,Ph,OH,Me)的电子结构研究

运用G98W，采用STO－3G基组，对茂金属配合物{o－[OPh(CO2)(R)]Zr(C5H4SiMe3)2}（R：（1）.NO2，（2）.CN,(3).Ph,(4).OH,(5).Me)进行从头算研究，探讨这些配合物结构单元的稳定性、分子轨道能量、原子净电荷布居规律，以及一些前沿分子轨道的组成特征等，为催化活性研究和分子设计提供理论参考。     

Low-Temperature Selective Catalytic Reduction of NO with NH<Subscript>3</Subscript> over Fe–Ce–O<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Catalysts

In this study, we used a simple impregnation method to prepare Fe–Ce–O _x catalysts and tested them regarding their low-temperature (200–300 °C) selective catalytic reduction (SCR) of NO using NH₃. We investigated the effects of Fe/Ce molar ratio, the gas hourly space velocity (GHSV), the stability and SO₂/H₂O resistance of the catalysts. The results showed that the FeCe(1:6)O _x (Ce/Fe molar ratio is 1:6) catalyst, which has some ordered parallel channels, exhibited good SCR performance. The FeCe(1:6)O _x catalyst had the highest NO conversion with an activity of 94–99% at temperatures between 200 and 300 °C at a space velocity of 28,800 h^?1. The NO conversion for the FeCe(1:6)O _x catalyst also reached 80–98% between 200 and 300 °C at a space velocity of 204,000 h^?1. In addition, the FeCe(1:6)O _x catalyst demonstrated good stability in a 10-h SCR reaction at 200–300 °C. Even in the presence of SO₂ and H₂O, the FeCe(1:6)O _x catalyst exhibited good SCR performance.     

Ionic Liquid-Complex Pd/C System as Catalyst for Copolymerization of CO and Styrene简

The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones(PK)was studied in the N-valeronitrile-N'-methylimidazolium hexafluorophosphate([C4CNmim]+PF-6) medium. The synthesized PK was characterized by Fourier transform infrared(FTIR), elemental analysis, 13C-nuclear magnetic resonance(13C-NMR), differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and gel permeation chromatography(GPC). The supported ionic liquid film on the surface of Pd/C catalyst can prevent the products from covering the hole of active carbon due to its chemical stability and weak coordination ability with metal ions, and thus efficiently improve the catalytic activity. The effects of different amounts of ionic liquid on the catalytic activity and reusability of the catalyst and the molecular weight of PK were discussed. When the usage of ionic liquid is 10wt%(0.1 g ionic liquid / 1 g active carbon carrier) and the theoretical content of Pd2+ is 5wt%(0.05 g Pd2+/ 1 g active carbon carrier), the highest catalytic activity 2 963.64 gSTCO/(gPd·h) is achieved with the molecular weight and polydispersity index of PK as Mn=9 684, Mw=13 452 and Mw /Mn=1.389.     

Comparison of the effects of copper and lead on soil microbial biomass carbon and nitrogen in red soil

A laboratory incubation experiment was conducted to study the effect of copper as cupric sulfate (CuSO₄.5H₂O), and lead as lead acetate (Pb (OAc)₂) on the size of the microbial biomass in red soil. The metals were applied, separately at six different levels: Cu at 50, 100, 200, 300, 400, and 600 μg·g⁻¹ soil and Pb at 100, 200, 400, 600, 800, and 1000 μg·g⁻¹ soil. In comparison to uncontaminated soil, the microbial biomass carbon (C_mic) and biomass nitrogen (N_mic) decreased sharply in soils contaminated with Cu and Pb. The microbial biomass C:N ratio in the metal contaminated soil was observed to be considerably higher than that in untreated control. Between the two tested metals, Cu displayed greater biocidal effect on microbial biomass carbon and nitrogen than Pb, showing their relative toxicity in the order: Cu≫Pb. Project (No. 49671050) supported by National Natural Science Foundation of China. Wa’el Mohamad—Former Ph. D. Student of Zhejiang University and is working in Ministry Of Agriculture (P. O. box. 2099), Amman, Jordan.     

Catalytic Activity of Cr(VI) in the Degradation of Phenol by H2O2 Under Acidic Conditions

Cr(VI) and phenol are toxic contaminants that need to be treated, and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater. In this study, Cr(VI) was used as a novel Fenton-like catalyst in phenol degradation by H₂O₂. In the pH range of 3.0‒11.0, the degradation efficiency of phenol decreased with elevated pH. At pH = 3.0, 100 mg/L phenol was effectively degraded by 2 mmol/L Cr(VI) and 20 mmol/L H₂O₂. At pH = 7.0 and the same conditions as those of pH = 3.0, 79% of 100 mg/L phenol was removed within 6 h, which was an improvement in pH limitation compared with the Fe(II)-mediated Fenton reaction. Quenching experiments indicated that ^·OH generated from the catalysis of H₂O₂ by Cr(V) instead of Cr(VI) was the primary oxidant that degraded phenol. When pyrophosphate was added in the Cr(VI)/H₂O₂ system, complexes with the Cr(V) intermediate rapidly formed and inhibited H₂O₂ decomposition, implying that the decomposition of H₂O₂ to ^·OH was catalyzed by Cr(V) instead of Cr(VI). The presence of anions such as chloride and sulfate had insignificant effect on the degradation of phenol. TOC and UV analyses suggest that phenol could not be completely oxidized to CO₂ and H₂O, and the intermediates identified by high performance liquid chromatography further indicates that maleic acid and benzoquinone were intermediates which may be further degraded into short chain acids, primarily maleic, formic, acetic, and oxalic acids, and eventually into CO₂ and H₂O. Considering that more than 50% Cr(VI) can also be removed during this process, the Cr(VI)/H₂O₂ system is more appropriate for the simultaneous removal of Cr(VI) and phenol contaminants from industrial wastewater.

     

Iron determination after on-line sorbent preconcentration by fi-fass using 1, 10-phenanthroline as a complexing agent

1, 10-Phenanthroline (phen) was tested as a complexing agent for on-line preconcentration of iron on RP-C₁₈ material in a microcolumn with flow injection coupled with flame atomic absorption spectrometer (FI-FAAS). The on-line formed Fe(II)-phen complexes were adsorbed on the C₁₈ sorbent material. Various parameters affecting the on-line Fe(II)-phen complex formation and its subsequent adsorption in the microcolumn as well as its elution into the nebulizer of AAS were optimized. A 2.5×10⁻³ mol/L phen in 2% through the microcolumn for 30 s. The adsorbed Fe(II)-phen complexes in the microcolumn were eluted with ethanol in 10 s into the nebulizer of AAS. Ascorbic acid (5×10⁻⁴ mol/L) was added to the sample solution for the reduction of Fe(III) to Fe(II). A good precision (RSD=1.1%,n=10), high enrichment factor (19) and sample throughput (90 h⁻¹) with detection limit (3σ) of 3 μg/L were obtained. The method was applied on standard reference materials (i. e. mussel and tomato leaves,) for iron determination and yielded results agreeing well with certified values. Project supported by the Zhejiang Provincial Natural Science Foundation of China and Zhejiang Environmental Protection Foundation From Pakistan Institute of Nuclear Science & Technology, Islamabad, Pakistan and now ZJ University, Ph. D. student.     

Novel Method for Preparing a Carbon Nanotube-Supported Cobalt Catalyst for Fischer–Tropsch Synthesis:Hydrogen Dielectric-Barrier Discharge Plasma

Hydrogen dielectric-barrier discharge (H₂-DBD) plasma was successfully used to prepare carbon nanotubes (CNTs)-supported cobalt (Co) catalyst. The H₂-DBD plasma treatment simultaneously decomposed and reduced the cobalt precursor at a lower temperature and in a shorter time than the conventional method (calcination and hydrogen reduction). It is considered that the H₂-DBD plasma method can remarkably decrease the amount of energy input compared to traditional methods used to prepare the Co-based catalyst in Fischer–Tropsch synthesis (FTS). Results showed that the Co catalyst prepared by H₂-DBD plasma had an equivalent catalytic performance for FTS as that prepared using the conventional method in calcination and hydrogen reduction, thereby determining that H₂-DBD plasma was an effective alternative treatment for preparing the Co/CNTs catalyst for FTS. This technology will provide a new strategy for preparing catalysts in other catalysis processes.     

Self-organizing evolution of anodized oxide films on Ti-25Nb-3Mo-2Sn-3Zr alloy and hydrophilicity

In the present work,hierarchical nanostructured titanium dioxide（TiO2） films were fabricated on Ti-25Nb-3Mo-2Sn-3Zr（TLM） alloy for biomedical applications via one-step anodization process in ethylene glycolbased electrolyte containing 0.5wt% NH4F.The nanostructured TiO2 films exhibited three distinct types depending on the anodization time：top irregular nanopores（INP）/beneath regular nanopores（RNP）,top INP/middle regular nanotubes（RNT）/bottom RNP and top RNT with underlying RNP.The evolution of the nanostructured TiO2 films with anodization time demonstrated that self-organizing nanopores formed at the very beginning and individual nanotubes originated from underlying nanopore dissolution.Furthermore,a modified two-stage self-organizing mechanism was introduced to illustrate the growth of the nanostructured TiO2 films.Compared with TLM titanium alloy matrix,the TiO2 films with special nano-structure hold better hydrophilicity and higher specific surface area,which lays the foundation for their biomedical applications.