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71.
Guoyi Bai Chenfang Zhang Yuecheng Zhang Haijun Yu Fei He Huisen Ning Ligong Chen 《Reaction Kinetics and Catalysis Letters》2007,90(2):373-380
The racemization of R-(-)-2-amino-1-butanol in a reaction using Co/γ-Al2O3 catalysts and catalysts modified by Mg or Ca was investigated in this paper. Complete racemization was achieved with a yield
of over 83% at using the Mg modified Co/γ-Al2O3 catalyst under optimized reaction conditions of 170°C and 2.5 MPa of H2. The catalysts were thoroughly characterized by XRD, XPS, TPR, SEM and TEM. The addition of Mg and Ca may be advantageous
for dispersing and stabilizing the active species of the Co/γ-Al2O3 catalyst, protecting from sintering, significantly improving its catalytic activity and stability. 相似文献
72.
Effect of epitaxial growth on the formation of the cobalt catalysts of the Fischer-Tropsch synthesis
Ya. V. Mikhailova S. A. Sviderskii M. N. Mikhailov I. V. Mishin V. Z. Mordkovich 《Russian Chemical Bulletin》2007,56(9):1922-1926
Mixed oxides CoxAlyO4 with different Al/Co ratios applied as supports for the catalysts of the Fischer-Tropsch synthesis were prepared using the
solid-state chemical reaction. The CoxAlyO4 supports were prepared by modifying gibbsite with various cobalt salts (acetate, nitrate, and basic carbonate). The use of
basic cobalt carbonate gives the Co(20%)/CoxAlyO4 catalyst, which provides an increased yield of hydrocarbons C5+ and a decreased methane content compared to the impregnation catalyst Co(30%)/Al2O3. The introduction of small amounts of rhenium additives makes it possible to enhance the yield of hydrocarbons C5+ (179 g m−3) and also to increase the selectivity with respect to the C5–C18 fraction. The introduction of basic cobalt carbonate into the support, most likely, creates favorable conditions for the
epitaxial growth of the precursor of the active phase.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1856–1860, September, 2007. 相似文献
73.
The thermal decomposition of Co(NO3)2·6H2O (1) as well as that one of NO[Co(NO3)3] (Co(NO3)2·N2O4) (2) was followed by thermogravimetric (TG) measurements, X-ray recording and Raman and IR spectra. The stepwise decomposition reactions of 1 and 2 leading to anhydrous cobalt(II)nitrate (3) were established. In N2 atmosphere, cobalt oxides are finally formed whereas in H2/N2 (10% H2) cobalt metal is produced. Rapid heating of cobalt(II)nitrate hexahydrate causes melting (formation of a hydrate melt) and therefore side reactions in the hydrate melt by incoupled reactions and evolution/evaporation of different species as, e.g., HNO3, NO2, etc. In case of larger amounts in dense packing in the sample container, the formation of oxo(hydoxo)nitrates is possible at higher temperature. For 2, its thermal decomposition to 3 was followed and its decomposition mechanism is proposed. 相似文献
74.
75.
The complexes of 4-chloro-2-methoxybenzoic acid anion with Mn2+,
Co2+, Ni2+, Cu2+
and Zn2+ were obtained as polycrystalline solids
with general formula M(C8H6ClO3)2·nH2O and colours typical for M(II) ions (Mn – slightly pink, Co –
pink, Ni – slightly green, Cu – turquoise and Zn – white).
The results of elemental, thermal and spectral analyses suggest that compounds
of Mn(II), Cu(II) and Zn(II) are tetrahydrates whereas those of Co(II) and
Ni(II) are pentahydrates. The carboxylate groups in these complexes are monodentate.
The hydrates of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II)
and Zn(II) heated in air to 1273 K are dehydrated in one step in the range
of 323–411 K and form anhydrous salts which next in the range of 433–1212
K are decomposed to the following oxides: Mn3O4,
CoO, NiO and ZnO. The final products of decomposition of Cu(II) complex are
CuO and Cu. The solubility value in water at 293 K for all complexes is in
the order of 10–3 mol dm–3.
The plots of χM
vs.
temperature of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II)
follow the Curie–Weiss law. The magnetic moment values of Mn2+,
Co2+, Ni2+ and Cu2+
ions in these complexes were determined in the range of 76−303 K and
they change from: 5.88–6.04 μB for Mn(C8H6ClO3)2·4H2O, 3.96–4.75
μB for Co(C8H6ClO3)2·5H2O, 2.32–3.02 μB for Ni(C8H6ClO3)2·5H2O and 1.77–1.94
μB for Cu(C8H6ClO3)2·4H2O. 相似文献
76.
A new utility for multipurpose analysis, SOLVERSTAT, taking advantage of the versatility of spreadsheets is here described. By means of this tool advanced statistical tests have introduced in Microsoft Excel Solver thus allowing regression diagnostic and discrimination between different models. The utility is here applied to the determination, by UV-Vis spectroscopy, of the stability constant for the uptake of molecular dioxygen by the 1:2 complex of Co(II) with N,N′-dimethylethylenediamine (dmen) in the aprotic solvent dimethylsulfoxide (dmso) at 298 K and in a medium adjusted to 0.1 mol dm−3 with Et4NClO4. The reliability of the model and parameters obtained are discussed and the results compared with those obtained by Dynafit, a different software package, and by independent voltammetric measurements. The validity of SOLVERSTAT has been also examined applying it to the discrimination between different models already discussed in the literature. 相似文献
77.
Bunichiro Yamada Shinji Tagashira Shuzo Aoki 《Journal of polymer science. Part A, Polymer chemistry》1994,32(14):2745-2754
The dimerization of methyl methacrylate, ethyl methacrylate, methacrylonitrile, and α-methylstyrene to 2-substituted-1-allylic compounds [CH2?C(X)CH2C(CH3)2X] (X = COOR, C6H5, or CN), and methyl α-ethylacrylate to a 3-substituted-2-allylic compound [CH3CH?C(COOCH3)CH2C(CH3)(C2H5) COOCH3] was carried out by catalytic chain transfer using benzylbis (dimethylglyoximato) (pyridine) cobalt (III). These dimers were then used as addition-fragmentation chain transfer agents in the polymerizations of methyl methacrylate and styrene at 800C or above. Cross-dimers from methacrylic ester-α-methylstyrene and methacrylonitrile-α-methylstyrene mixtures were similarly prepared. Except for those from methyl α-ethylacrylate and methacrylonitrile, all the dimers participated in the addition-fragmentation and the copolymerization to different extents. The dimer of methyl α-ethylacrylate was actually inactive during the styrene and methyl methacrylate polymerizations. The methacrylonitrile dimer was primarily incorporated in the polymer chain through copolymerization. Among the dimer and the cross-dimers from α-methylstyrene with the other monomers, those bearing the α-methylstyrene moiety in the α-substituent [CH2?C(X)CH2C(CH3)2C6H5, X?COOCH3, COOC2H5, and CN] are noted as highly reactive chain transfer agents. © 1994 John Wiley & Sons, Inc. 相似文献
78.
>为获得综合性能更好的锂离子二次电池正极材料, 分析了Co掺杂对LixNiO2电化学性能的影响. 采用密度泛函DFT理论对LixNiO2和LixNi0.5Co0.5O2的平均放电电压和态密度进行了计算. 同时, 用共沉淀法制备了LixNiO2和LixNi0.5Co0.5O2锂离子二次电池正极材料, 并对其进行了XRD结构分析和恒流充放电测试. 实验和计算结果表明: 随锂离子嵌入正极(电池放电), 电池的电压逐渐降低, 材料的态密度峰向低能量方向移动; 与LixNiO2相比, LixNi0.5Co0.5O2的电压平台相对较高(当0.25≤x≤0.5), 而且在Li+嵌/脱时, LixNi0.5Co0.5O2的结构变化相对较小; Co离子的掺入, 减小了NiO6八面体的畸变度, 使材料的电化学稳定性得以提高. 在钴掺杂镍酸锂体系中, NiO6和CoO6具有相互的稳定作用. 相似文献
79.
80.
Two new complexes, (CoIII)2(H3L?)2(0.5H2O)2(ClO4)4 (I) and (MnIII)2(H3L?)2(0.5H2O)2 (ClO4)4 (II), were synthesized and crystallographically characterized [H4L = 1,4,7,10‐tetra‐(2‐hydroxypropyl)‐l,4,7,10‐tetraazacyclododecane] using electrospray ionization mass spectrometry and X‐ray photoelectron spectrometery. The characterizations confirmed that the valences of the metal ions increased from divalent to trivalent due to deprotonation of one OH group (H4L was in the form of H3L?). Owing to the instability of Co(III) and Mn(III) in both air and in solution, they preferred to exist in divalent form. The two heptadentate complexes are extraordinary in that the chiral pendants of the complexes are different in configuration. Spectroscopic studies, viscosity measurements, thermal denaturation experiments and circular dichroism spectra demonstrated that the complexes were prone to interact with DNA by groove binding. At micromolar concentrations and under physiological conditions, the two complexes were able to oxidatively cleave the supercoiled pUC19 plasmid DNA into its nicked and linear forms. Mechanistic studies using various additives suggest the complexes had structures different from those of other inorganic complexes. These are the first reported inorganic complexes not containing planar aromatic ligands and yet binding at the major groove. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献