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71.
铁酸钴纳米微粒的共沉淀法制备和磁性质(英) 总被引:5,自引:0,他引:5
The cobalt ferrite nanoparticles were prepared by coprecipitation in the presence of poly (N-vinylpyrrolidone) (PVP) and characterized by XRD, TEM, EDX and magnetometry. XRD results suggest the formation of pure cobalt ferrite. The mean particle sizes of CoFe2O4 samples annealed at 400 ℃ and 600 ℃ were ca. 6 and 25 nm, respectively as obtained by transmission electron microscopy (TEM). The magnetic measurements indicated that nano-particles obtained at 400 ℃ were superparamagnetic while that prepared at 600 ℃ were ferrimagnetic. 相似文献
72.
A new cobalt(Ⅱ) complex, [CoL2(NCS)2]·2CH2Cl2, [L=4-(p-methylphenyl)-3,5-bis(pyridin-2-yl)-1,2,4-triazole], was synthesized and its crystal structure was determined by X-ray analysis. The complex crystallizes in monoclinic system with space group P21/c, a=0.867 40(17), b=1.453 9(3), c=1.781 9(4) nm, β=91.18(3)°, V=2.246 7(8) nm3 and Z=2. The cobalt atom is in a distorted octahedral environment with two bidentate chelating L ligands in the equatorial plane and two NCS- ions in the axial positions. CCDC: 251658. 相似文献
73.
采用脉冲D2反应研究了CeO2在Co-CeO2/SiO2费托合成催化剂中的作用机理. 通过比较在Co-CeO2/SiO2和Co/SiO2催化剂上的脉冲D2反应实验结果发现, CeO2可以提高载体表面 Si-OH 的H-D同位素交换活性和 Si-OH 中H参与CO加氢反应的活性; CeO2不仅增加了催化剂表面活性碳物种的总量,而且活性碳物种以链增长单体-CH2-为主,因而有利于增加费托合成反应速率和链增长几率; CeO2的加入明显提高了催化剂表面碳原子的加氢反应速率,从而减少了碳沉积. 相似文献
74.
Cobalt(II) complexes of poly(aryl ester) dendrimer porphyrins [(m-[Gn]TPP)Co(II)] (generation number n=0-4), in the presence of azobisisobutyronitrile (AIBN) at 60 degrees C, underwent alkenylation with several alkynes at the metal center. A complete inhibition of double-bond migration (secondary transformation) was observed for [(m-[Gn]TPP)Co(II)] (n=3 and 4), which gave [(m-[Gn]TPP)Co(III)-C(=CH(2))R] (n=3 and 4) exclusively. Overall reaction rates for [(m-[Gn]TPP)Co(II)] (n=0-3) were hardly dependent on the size of the dendritic substituents, while a notable retardation was observed for the largest dendrimer, [(m-[G4]TPP)Co(II)]. Mechanistic studies on double-bond migration with pure [(m-[Gn]TPP)Co(III)-C(=CH(2))Bu] (n=0-4) demonstrated that the secondary transformation involves participation of [(m-[Gn]TPP)Co(III)H] (n=0-4), derived from [(m-[Gn]TPP)Co(II)] and AIBN, rather than [(m-[Gn]TPP)Co(II)] alone. Crossover experiments using [(m-[Gn]TPP)Co(III)-C(=CH(2))Bu] (n=2-4), in combination with nondendritic [(m-[G0]TPP)Co(II)] and AIBN, indicated a high level of steric protection of the active center by a robust [G4]-dendritic cage, as suggested by a (1)H NMR pulse relaxation time profile of m-[G4]TPPH(2). 相似文献
75.
含有不同配体的钴配合物/EAO催化乙烯齐聚 总被引:2,自引:0,他引:2
考察了(bipy)CoCl2,(C6H5N=C-C6H4-o-O)2Co和(acac)2CO 3种配合物与EAO组成的二元催化体系A,B和C,在不同的反应温度,铝钴比以及不同反应时间对乙烯齐聚催化活性和选择性的影响,结果表明,3种催化体系都对催化乙烯齐聚反应有活性,在相同的反应条件下,3种催化体系对乙烯齐聚的催化活性顺序为:A>B>C,在反应温度为180摄氏度时,催化体系(bipy)CoCl2/EAO的活性为2441g/(gCo.H),产物中低碳烯烃的选择性为95.9%。 相似文献
76.
Ion Association and Hydration in Aqueous Solutions of Nickel(II) and Cobalt(II) Sulfate 总被引:1,自引:0,他引:1
Ting?Chen Glenn?HefterEmail author Richard?Buchner 《Journal of solution chemistry》2005,34(9):1045-1066
Aqueous solutions of nickel(II) and cobalt(II) sulfate have been investigated at 25 ∘C by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 ≤ ν (GHz) ≤ 89) and salt concentrations
(0.025 ≤ c(mol-L−1) ≤ 1.4). The spectra indicate, as for MgSO4(aq) studied previously, the simultaneous presence of double solvent-separated, solvent-shared and contact ion pairs in both
NiSO4(aq) and CoSO4(aq). The stepwise formation constants for each ion-pair type and the overall association constant, obtained from the data
are in good agreement with ultrasonic relaxation and other estimates. The DR spectra at higher concentrations (c ≥ 0.5 mol-L−1) suggest the existence of a nonlinear triple ion M2SO42+(aq). Consistent with the very strong hydration of the salts, which have ‘effective’ hydration numbers approaching 27 at infinite
dilution, there are no significant differences in any of the relaxation or thermodynamic parameters for NiSO4(aq) and CoSO4(aq), except that the triple ion appears to be somewhat more stable for the latter. 相似文献
77.
A. Müller E. Krickemeyer F. El-Katri D. Rehder A. Stammler H. Bgge F. Hellweg 《无机化学与普通化学杂志》1995,621(7):1160-1170
Simple Trithio- and Perthiocarbonato Complexes with Interesting Bond Properties: [E(CS3)2]2? (E = Sn, Zn, Cd), [E(CS3)3]3? (E = As, Sb, Bi, Co), {Cu(CS3)?}∞ and [Zn(CS4)2]2? By reactions of potassium trithiocarbonate ( 1 ) with solutions of zinc(II)- acetylacetonate, cadmium(II)-chloride, tin(II)-chloride, arsenic(III)-sulfide (suspension), antimony(III)-chloride, bismuth(III)-chloride and copper(II)-chloride in dimethyl sulfoxide, as well as of trisodium hexanitrito cobaltate(III) in water, and the precipitation of the complexes with an aqueous solution of tetraphenylphosphonium chloride the compounds (PPh4)2[Zn(CS3)2] ( 2 ), (PPh4)2[Cd(CS3)2] ( 3 ), (PPh4)2[Sn(CS3)2] ( 4 ), (PPh4)3[As(CS3)3] ( 5 ), (PPh4)3[Sb(CS3)3] ( 6 ), (PPh4)3[Bi(CS3)3] ( 7 ), (PPh4)3[Co(CS3)3] ( 8 ) and (PPh4)Cu(CS3) ( 9 ) have been isolated. (PPh4)2[Zn(CS4)2] · CH3NO2 ( 10 ) has been prepared by heating a solution of 2 in nitromethane to 60--70°C in presence of air. The reaction of 1 in dimethyl sulfoxide with an aqueous tetraphenylphosphonium chloride solution in presence of oxygen leads to (PPh4)2[C2S6] ( 11 ). The compounds have been characterized by spectroscopical studies (IR, Raman, UV/Vis, 113Cd/59Co-NMR), magnetic susceptibility measurements, powder diffractometry, elemental analyses and single crystal X-ray structure analysis ( 4 – 7 , 10 and 11 ). The difficult growing of single crystals has been reported in detail. For crystal data see Inhaltsübersicht. 相似文献
78.
催化褪色光度法测定痕量钴的研究 总被引:15,自引:2,他引:15
研究了在PH10.5的Na2B4O7-NaOH介质中,痕量钴(Ⅱ)对过氧化氢氧化桑色素初色反应的催化作用,建立了催化动力学光度法测定痕量钴的新方法。方法的线性范围为0-1.2μ/mL检出限为4.4*10^-18g/L。用于水和维生素B12中钴的测定,结果满意。 相似文献
79.
Thermochemical Investigations of the Systems Ti/Ni and Ti/Co By treatment of solid Ni or Co with a H2/TiCl4-gas mixture at sufficient high temperature (T ≥ 900°C) the intermetallic phases TiNi3 and TiCo3, resp., are formed. The conversion grade depends on the H2/TiCl4-ratio. From the experimentally determined conversion grades and the known thermodynamic data of all other species existing in equilibrium the free enthalpies and the heats of formation of TiN3 and TiCo3 have been calculated (TiNi3: ΔH(298) = ?133.3 ± 6 kJ/mol; TiCo3: ΔH(298) = ?104.7 ± 6 kJ/mol). 相似文献
80.
Mingdeng Wei Kiyomi Okabe Hironori Arakawa Yesutake Teraoka 《Reaction Kinetics and Catalysis Letters》2002,77(2):381-387
SiO2 was modified by hexagonal mesoporous silica to form a mixture with meso-/macroporous sizes and used as support of Co catalysts for Fischer-Tropsch synthesis in a slurry phase. A synergistic effect on the activity of Co catalyst was found. The catalytic properties are related to the state of surface Co and the character of support. 相似文献