Showing papers on "Cobalt published in 2006"
TL;DR: X-ray absorption spectroscopy revealed that cobalt was metallic, even for small particle sizes, after the in situ reduction treatment, which is a prerequisite for catalytic operation and is difficult to achieve using traditional oxidic supports.
Abstract: The influence of cobalt particle size in the range of 2.6-27 nm on the performance in Fischer-Tropsch synthesis has been investigated for the first time using well-defined catalysts based on an inert carbon nanofibers support material. X-ray absorption spectroscopy revealed that cobalt was metallic, even for small particle sizes, after the in situ reduction treatment, which is a prerequisite for catalytic operation and is difficult to achieve using traditional oxidic supports. The turnover frequency (TOF) for CO hydrogenation was independent of cobalt particle size for catalysts with sizes larger than 6 nm (1 bar) or 8 nm (35 bar), while both the selectivity and the activity changed for catalysts with smaller particles. At 35 bar, the TOF decreased from 23 x 10(-3) to 1.4 x 10(-3) s(-1), while the C5+ selectivity decreased from 85 to 51 wt % when the cobalt particle size was reduced from 16 to 2.6 nm. This demonstrates that the minimal required cobalt particle size for Fischer-Tropsch catalysis is larger (6-8 nm) than can be explained by classical structure sensitivity. Other explanations raised in the literature, such as formation of CoO or Co carbide species on small particles during catalytic testing, were not substantiated by experimental evidence from X-ray absorption spectroscopy. Interestingly, we found with EXAFS a decrease of the cobalt coordination number under reaction conditions, which points to reconstruction of the cobalt particles. It is argued that the cobalt particle size effects can be attributed to nonclassical structure sensitivity in combination with CO-induced surface reconstruction. The profound influences of particle size may be important for the design of new Fischer-Tropsch catalysts.
1,326 citations
TL;DR: In this article, the surface area changes of platinum (Pt) based catalysts supported on carbon were evaluated using an accelerated durability test (ADT) and the results obtained using the ADT were correlated to the performance of the Pt-based catalysts in the fuel cell, and the Pt catalyst exhibited loss of active surface area, and a resulting decrease in the oxygen reduction reaction (ORR) activity was observed.
456 citations
TL;DR: The structures, the energetics, and the charge distribution of the betaine cation and the bis(trifluoromethylsulfonyl)imide anion, as well as the cation-anion pairs, were studied by density functional theory calculations.
Abstract: Protonated betaine bis(trifluoromethylsulfonyl)imide is an ionic liquid with the ability to dissolve large quantities of metal oxides. This metal-solubilizing power is selective. Soluble are oxides of the trivalent rare earths, uranium(VI) oxide, zinc(II) oxide, cadmium(II) oxide, mercury(II) oxide, nickel(II) oxide, copper(II) oxide, palladium(II) oxide, lead(II) oxide, manganese(II) oxide, and silver(I) oxide. Insoluble or very poorly soluble are iron(III), manganese(IV), and cobalt oxides, as well as aluminum oxide and silicon dioxide. The metals can be stripped from the ionic liquid by treatment of the ionic liquid with an acidic aqueous solution. After transfer of the metal ions to the aqueous phase, the ionic liquid can be recycled for reuse. Betainium bis(trifluoromethylsulfonyl)imide forms one phase with water at high temperatures, whereas phase separation occurs below 55.5 degrees C (temperature switch behavior). The mixtures of the ionic liquid with water also show a pH-dependent phase behavior: two phases occur at low pH, whereas one phase is present under neutral or alkaline conditions. The structures, the energetics, and the charge distribution of the betaine cation and the bis(trifluoromethylsulfonyl)imide anion, as well as the cation-anion pairs, were studied by density functional theory calculations.
416 citations
TL;DR: In this article, the complexity of intergrown and disordered LiMO 2 systems with trivalent cobalt and tetravalent manganese and divalent nickel was discussed.
414 citations
TL;DR: In this paper, the performance of composite oxides with different cobalt loading (5, 15, 30, 50, 70, 80, 90, 95, and 95% of the oxides were investigated for the oxidation of methane under stoichiometric conditions.
Abstract: Co 3 O 4 /CeO 2 composite oxides with different cobalt loading (5, 15, 30, 50, 70 wt.% as Co 3 O 4 ) were prepared by co-precipitation method and investigated for the oxidation of methane under stoichiometric conditions. Pure oxides, Co 3 O 4 and CeO 2 were used as reference. Characterization studies by X-ray diffraction (XRD), BET, temperature programmed reduction/oxidation (TPR/TPO) and X-ray photoelectron spectroscopy (XPS) were carried out. An improvement of the catalytic activity and thermal stability of the composite oxides was observed with respect to pure Co 3 O 4 in correspondence of Co 3 O 4 –CeO 2 containing 30% by weight of Co 3 O 4 . The combined effect of cobalt oxide and ceria, at this composition, strongly influences the morphological and redox properties of the composite oxides, by dispersing the Co 3 O 4 phase and promoting the efficiency of the Co 3+ –Co 2+ redox couple. The presence in the sample Co 3 O 4 (30 wt.%)–CeO 2 of a high relative amount of Ce 3+ /(Ce 4+ + Ce 3+ ) as detected by XPS confirms the enhanced oxygen mobility. The catalysts stability under reaction conditions was investigated by XRD and XPS analysis of the used samples, paying particular attention to the Co 3 O 4 phase decomposition. Methane oxidation tests were performed over fresh (as prepared) and thermal aged samples (after ageing at 750 °C for 7 h, in furnace). The resistance to water vapour poisoning was evaluated for pure Co 3 O 4 and Co 3 O 4 (30 wt.%)–CeO 2 , performing the tests in the presence of 5 vol.% H 2 O. A methane oxidation test upon hydrothermal ageing (flowing at 600 °C for 16 h a mixture 5 vol.% H 2 O + 5 vol.%O 2 in He) of the Co 3 O 4 (30 wt.%)–CeO 2 sample was also performed. All the results confirm the superiority of this composite oxide.
403 citations
TL;DR: In this article, it was found that performing the reaction at >120oC leads to fast formation of a single void inside each shell, whereas at room-temperature multiple voids are formed within each shell.
Abstract: Formation of cobalt sulfide hollow nanocrystals through amechanism similar to the Kirkendall Effect has been investigated indetail. It was found that performing the reaction at>120oC leads tofast formation of a single void ins ide each shell, whereas at roomtemperature multiple voids are formed within each shell, which can beattributed to strongly temperature-dependent diffusivities for vacancies.The void formation process is dominated by outward diffusion of cobaltcations; still, significant inward transport of sulfur anions can beinferred to occur as the final voids are smaller in diameter than theoriginal cobalt nanocrystals. Comparison of volume distributions forinitial and final nanostructures indicates excess apparent volume inshells implying significant porosity and/or a defective structure.Indirect evidence for shells to fracture during growth at lowertemperatures was observed in shell size statisticsand TEM of as-grownshells. An idealized model of the diffusional process imposes two minimalrequirements on material parameters for shell growth to be obtainablewithin a specific synthetic system.
351 citations
TL;DR: The presence of light and heavy metal ions influenced the copper and cobalt uptake potential of crab shell and among several eluting agents, EDTA (pH 3.5, in HCl) performed well and also caused low biosorbent damage.
339 citations
336 citations
TL;DR: In this paper, the key advances that have occurred in the discovery and development of 2,6-bis(imino)pyridyl iron(II) and cobalt-II catalysts for the transformation of ethylene into linear and branched homopolymers or into α-olefins with either Schulz-Flory or Poisson distribution are highlighted.
331 citations
TL;DR: In this paper, a new PVC membrane electrode for Co 2+ based on N,N ′-bis(salicylidene)-3,4-diaminotoluene, an excellent neutral carrier, has been fabricated using sodium tetraphenylborate (NaTPB) as an anionic excluder and dioctylphthalte (DOP) as a solvent mediator.
327 citations
TL;DR: In this article, catalysts based on nickel and cobalt were developed to accelerate the hydrolysis reaction for hydrogen generation for borohydrides, a group of compounds with large hydrogen contents.
TL;DR: The sorption process followed pseudo-second-order kinetics with necessary time of 24 h to reach equilibrium, and the desorbed amount of cobalt decreased continuously with increasing pH, and increased with increasing Ca(2+) concentration in leaching solution.
TL;DR: Nickel/cobalt transporters of different families, including the previously known NiCoT, UreH, and HupE/UreJ families of secondary systems and the NikABCDE ABC-typetransporters, showed a mosaic distribution in prokaryotic genomes.
Abstract: The transition metals nickel and cobalt, essential components of many enzymes, are taken up by specific transport systems of several different types. We integrated in silico and in vivo methods for the analysis of various protein families containing both nickel and cobalt transport systems in prokaryotes. For functional annotation of genes, we used two comparative genomic approaches: identification of regulatory signals and analysis of the genomic positions of genes encoding candidate nickel/cobalt transporters. The nickel-responsive repressor NikR regulates many nickel uptake systems, though the NikR-binding signal is divergent in various taxonomic groups of bacteria and archaea. B12 riboswitches regulate most of the candidate cobalt transporters in bacteria. The nickel/cobalt transporter genes are often colocalized with genes for nickel-dependent or coenzyme B12 biosynthesis enzymes. Nickel/cobalt transporters of different families, including the previously known NiCoT, UreH, and HupE/UreJ families of secondary systems and the NikABCDE ABC-type transporters, showed a mosaic distribution in prokaryotic genomes. In silico analyses identified CbiMNQO and NikMNQO as the most widespread groups of microbial transporters for cobalt and nickel ions. These unusual uptake systems contain an ABC protein (CbiO or NikO) but lack an extracytoplasmic solute-binding protein. Experimental analysis confirmed metal transport activity for three members of this family and demonstrated significant activity for a basic module (CbiMN) of the Salmonella enterica serovar Typhimurium transporter.
TL;DR: Single-crystal X-ray diffraction of SIZ-7 is a novel zeolite structures that is closely related to the family of 8-ring zeolites consisting of the MER, GIS, and PHI frameworks, and indicates that the distribution of cobalt among the four possible tetrahedral sites is unequal.
Abstract: Ionothermal synthesis, the use of an ionic liquid as both solvent and structure-directing agent, has been used to synthesize three different cobalt aluminophosphate zeolites. Two of the materials are isostructural with solids prepared previously and have the AEI and SOD framework types. SIZ-7 is a novel zeolite structures that is closely related to the family of 8-ring zeolites consisting of the MER, GIS, and PHI frameworks. Single-crystal X-ray diffraction of SIZ-7 indicates that the distribution of cobalt among the four possible tetrahedral sites is unequal.
TL;DR: In this paper, the growth of carbon nanotubes (CNTs) was attempted using a vapor-phase CVD method, and a wide variety of transition metals, in the form of metallocenes and chlorides, were used as potential growth catalysts.
TL;DR: In this paper, the efficiency of coir pith for the adsorption of Co(II), Cr(III) and Ni(II) from single ion solutions as well as from a mixture of them was investigated using batch adsorization technique under different experimental conditions.
National Autonomous University of Mexico1, University of Bremen2, University of Arizona3, Centers for Disease Control and Prevention4, University of Turin5, Fraunhofer Society6, Vrije Universiteit Brussel7, Academy of Sciences of the Czech Republic8, University of Fukui9, François Rabelais University10, Université catholique de Louvain11, Health and Safety Executive12, Katholieke Universiteit Leuven13, National Institutes of Health14, Karolinska Institutet15, Battelle Memorial Institute16, European Commission17
TL;DR: Members Mario Altamirano-Lozano, Unidad de Investigación en Genética y Toxicología Ambiental (UNIGEN), Facultad de Estudios Superiores-Zaragoza, Battalla del 5 de mayo esq.
Abstract: Members Mario Altamirano-Lozano, Unidad de Investigación en Genética y Toxicología Ambiental (UNIGEN), Facultad de Estudios Superiores-Zaragoza, Battalla del 5 de mayo esq. Fuerte de Loreto Col. Ejercito de Oriente, C.P. 09230 Mexico, DF, Mexico Detmar Beyersmann, Department of Biology & Chemistry, Fachbereich 2, University of Bremen, Leobener Strasse NW2, Raum B2230, 28359 Bremen, Germany (Chairman) Dean E. Carter, Department of Pharmacology & Toxicology, Center for Toxicology, College of Pharmacy, University of Arizona, 1703 E. Mabel, Tucson, AZ 85721, USA (unable to attend) Bruce A. Fowler, Senior Research Advisor, ATSDR/CDC, 1600 Clifton Road NE, MS E-29, Atlanta, GA 30333, USA (Subgroup Chair: Other Relevant Data) Bice Fubini, Department of Inorganic, Physical & Material Chemistry and Interdepartmental Center ‘G. Scansetti’ for Studies on Asbestos and other Toxic Particulates, Facoltà di Farmacia, Università degli Studi di Torino, Via P. Giuria 7, 10125 Torino, Italy Janet Kielhorn, Fraunhofer Institute of Toxicology & Experimental Medicine, Department of Chemical Risk Assessment, Nikolai-Fuchs-Strasse 1, 30625 Hannover, Germany Micheline Kirsch-Volders, Laboratorium voor Cellulaire Genetica, Faculteit Wetenschappen, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Jan Kucera, Nuclear Physics Institute, 250 68 Rez near Prague, Czech Republic Yukinori Kusaka, Department of Environmental Health, School of Medicine, Fukui Medical University, Matsuoka-cho, Fukui 910-1193, Japan (Subgroup Chair: Exposure Data) Gerard Lasfargues, Médecine et Santé au Travail, Faculté de Médecine, 2 bis Bd Tonnelé, B.P. 3223, 37325 Tours Cedex, France Dominique Lison, Industrial Toxicology & Occupational Medicine Unit, Catholic University of Louvain, Clos Chapelle-aux-Champs 30, 1200 Brussels, Belgium IARC WORKING GROUP ON THE EVALUATION OF CARCINOGENIC RISKS TO HUMANS: COBALT IN HARD METALS AND COBALT SULFATE, GALLIUM ARSENIDE, INDIUM PHOSPHIDE AND VANADIUM PENTOXIDE
TL;DR: In situ metalation provides a convenient way to produce adsorbed monolayers of more reactive or thermally unstable metalloporphyrins that are difficult to evaporate or even to obtain as pure compounds at room temperature.
Abstract: We demonstrate that well-defined monolayers of a metal complex on a surface can be prepared by direct vapor deposition of the metal atoms on monolayers of the ligand. In particular, ordered monolayers of adsorbed tetraphenylporphyrin (2H-TPP) on a silver surface were exposed to cobalt vapors, resulting in the complexation of the metal by the porphyrin. The formation of the metal complexes was monitored by means of X-ray photoelectron spectroscopy (XPS), which reveals that this metalation reaction leads to a chemical equivalence of all four nitrogen atoms. The described in situ metalation provides a convenient way to produce adsorbed monolayers of more reactive (e.g., air- or solvent-sensitive) or thermally unstable metalloporphyrins that are difficult to evaporate or even to obtain as pure compounds at room temperature.
TL;DR: In this paper, it was shown that cobalt and nickel sulphides react versus lithium through conversion reactions similarly to their homologous oxides with during the discharge step the formation of metallic nano-particles embedded in Li2S that on the following charge convert back into sulphides.
TL;DR: Wires of hollow CoSe2 nanocry crystals form without loss of the preassembled nanostructure induced by the magnetic dipolar interactions of the cobalt nanocrystals through the nanoscale Kirkendall effect.
Abstract: Self-assembly, an attractive and practical methodology, allows the formation of a wide range of nanostructures for promising applications—for example, nanoparticle arrays for new optical band-gap materials or high-density magnetic recording media, self-assembled monolayers (SAM) for nanometerthick films on a variety of substrates, and nanofibers of selforganized small molecules or oligopeptides for drug delivery and tissue engineering. Hydrogen bonding and/or van der Waals interactions are usually the driving forces that result in self-assembly at the nanoscale. Despite extensive investigation, it is still difficult to control and predict the nanostructures resulting from these two types of forces. Although several recent reports have shown that magnetic dipolar interactions induce rather predictable nanoassemblies, methods for maintaining these assemblies when the magnetic force decreases or vanishes have been less thoroughly investigated. Therefore, we decided to use the magnetic dipoles inherently associated with magnetic nanoparticles to form 1D assemblies of hollow nanocrystals of semiconductors. We chose to make wires of hollow nanocrystals of CoSe2 to demonstrate the concept, because 1) the isolation of a nanonecklace of cobalt nanocrystals on a substrate from a dispersion after removal of the solvent indicated that magnetic dipolar interactions are sufficient to maintain 1D assemblies of nanocrystals in solution; 2) the recently reported formation of hollow CoSe nanocrystals from cobalt nanocrystals through the Kirkendall effect suggested that a similar process could be used to generate hollow CoSe2 nanocrystals from 1D assemblies of cobalt nanocrystals; 3) hollow nanostructures have received considerable attention because they exhibit properties that differ from their solid counterparts; and 4) nanowires of hollow nanocrystals of CoSe2 are unknown. Herein, we show that when their sizes reach approximately 20 nm cobalt nanocrystals self-assemble into wires in solution at temperatures as high as 455 K. Through the nanoscale Kirkendall effect, wires of hollow CoSe2 nanocrystals form without loss of the preassembled nanostructure induced by the magnetic dipolar interactions of the cobalt nanocrystals. In control experiments, when the size of the cobalt nanocrystals is 6 nm, or when 20-nm cobalt nanocrystals are in an alternating magnetic field, no wires of hollow CoSe2 nanocrystals form. These observations confirm that the magnetic interaction plays a key role in the formation of the nanowires of hollow CoSe2 crystals. Several types of ferromagnetic metallic nanocrystals (iron, cobalt, nickel, FePt, or CoPt) can be prepared readily, and their selfassembly depends on the magnetic dipolar interactions of particles of a certain size. Therefore, the method shown herein should be a general route to 1D assemblies of hollow nanocrystals. The synthesis of wires of hollow CoSe2 nanocrystals is easy and straightforward. Cobalt nanocrystals of approximately 20 nm in diameter were prepared according to a modified literature procedure and then dispersed in a solvent (for example, 1,2-dichlorobenzene) by using trioctylphosphine oxide (TOPO) as a surfactant. The injection of a dichlorobenzene solution of selenium into the dispersion of cobalt nanocrystals under reflux at 455 K resulted in a black dispersion of CoSe2 nanocrystals after approximately 30 min. Transmission electron microscope (TEM) images reveal that the CoSe2 nanocrystals form wires of intercon[*] J. Gao, Prof. B. Xu Department of Chemistry The Hong Kong University of Science & Technology Clear Water Bay, Hong Kong (China) Fax: (+852)2358-1594 E-mail: chbingxu@ust.hk
TL;DR: In this paper, homogeneous deposition-precipitation on either a silica or carbon nanofiber (CNF) support of cobalt from basic solution using ammonia evaporation was studied and compared with conventional deposition from an acidic solution using urea hydrolysis.
Abstract: Ni–Co alloys with varying cobalt content were electrodeposited employing sulphamate electrolyte. The changes in microstructure and corrosion behavior of electrodeposited nickel with respect to cobalt addition were studied. Scanning electron microscope, optical microscope and energy dispersive X-ray analysis were used to characterize the alloy coatings. The alloy co-deposition was observed to be anomalous type. The cross-section microhardness measurement indicated that the hardness reached the maxima for a cobalt content of 50 wt.% and then dropped with the increase in cobalt content. A correlation between microhardness and microstructure has been attempted. The optical micrographs indicated a change in microstructure from mixed columnar-fibrous to lamellar and finally to fibrous with increase in cobalt content. The X-ray diffraction (XRD) studies indicated the crystal structure to be cubic for cobalt content in the range of 0–50 wt.%. A transition to hexagonal structure was observed for a cobalt content of 70 wt.% and beyond. A change in preferred orientation was also observed with respect to cobalt addition. Potentiodynamic polarization and electrochemical impedance studies were used to study the corrosion behavior of Ni–Co alloys. The physical behavior was quantified with equivalent circuit. These studies indicated that the Ni–20% Co alloy exhibited better corrosion resistance in comparison to other Ni–Co alloys, plain nickel and plain cobalt coatings irrespective of the substrate (mild steel, brass) employed for deposition.
TL;DR: In this article, a review of the literature on the electrodeposition of nickel and its binary and selected ternary alloys with copper and cobalt is presented, along with the determination of the structure and morphology of the deposits on different substrates.
Abstract: The numerous theoretical and practical studies of the electrodeposition of nickel and its binary and selected ternary alloys with copper and cobalt over the last 10–15 years are reviewed. The reported mechanisms of the electrodeposition processes and accompanying evolution of hydrogen are considered. The complex influence of different bath compositions, pHs, current densities or potential ranges and temperature on the formation of single or multiple deposition layers are compared. The determination of the structure and morphology of the deposits on different substrates, including solid surfaces and particulate materials, using a range of analytical techniques are reported.
TL;DR: In this paper, a series of cobalt catalysts supported on silica with different pore size were prepared by incipient wetness impregnation method, and the results showed that the pore sizes of the support had a significant influence on the Co 3 O 4 crystallite diameter, catalyst reducibility and Fischer-Tropsch activity.
Abstract: A series of cobalt catalysts supported on silica with different pore size were prepared by incipient wetness impregnation method. N 2 physisorption, XRD, H 2 -TPR, H 2 -TPD, DRIFTS and O 2 pulse reoxidation were used to characterize the catalysts. The results showed that the pore size of the support had a significant influence on the Co 3 O 4 crystallite diameter, catalyst reducibility and Fischer–Tropsch activity. The larger pore could cause the Co/SiO 2 to form larger Co 3 O 4 crystallite and decreased its dispersion. Catalysts with different pore size showed different CO adsorption property. The catalysts with pore size of 6–10 nm displayed higher Fischer–Tropsch activity and higher C 5+ selectivity, due to the moderate particle size and moderate CO adsorption on the catalysts.
TL;DR: The essential ingredient in achieving room temperature ferromagnetism in these Zn(1-x)Co(x)O nanoparticles was found to be the presence of additional carriers generated by the presenceof the oxygen vacancies.
Abstract: We report the crystal structure and magnetic properties of Zn1−xCoxO (0≤x≤010) nanoparticles synthesized by heating metal acetates in organic solvent The nanoparticles were crystallized in the wurtzite ZnO structure after annealing in air and in a forming gas (Ar95% + H5%) The x-ray diffraction and x-ray photoemission spectroscopy (XPS) data for different Co content show clear evidence for the Co2+ ions in tetrahedral symmetry, indicating the substitution of Co2+ in the ZnO lattice However, samples with x = 008 and higher cobalt content also indicate the presence of Co metal clusters Only those samples annealed in the reducing atmosphere of the forming gas, that showed the presence of oxygen vacancies, exhibited ferromagnetism at room temperature The air annealed samples remained non-magnetic down to 77 K The essential ingredient in achieving room temperature ferromagnetism in these Zn1−xCoxO nanoparticles was found to be the presence of additional carriers generated by the presence of the oxygen vacancies
TL;DR: UV-vis spectroscopic measurements elucidate the typical green/blue color of an alpha-type cobalt hydroxide and indicate that the divalent cobalt were in local neighboring environments of both octahedral and tetrahedral coordination.
Abstract: We report a Rietveld refinement analysis and X-ray absorption study on a green-color Cl(-)-intercalated alpha-type cobalt hydroxide phase. The refinement clearly demonstrated that one-fifth to one-sixth of the Co(II) at octahedral sites was replaced by pairs of tetrahedrally coordinated Co(II) on each side of the hydroxide plane, represented by a structural formula of [Co(octa)(0.828)Co(tetra)(0.348)(OH)2](0.348+)Cl(0.348).0.456H2O. X-ray absorption spectroscopy also indicated that the divalent cobalt were in local neighboring environments of both octahedral and tetrahedral coordination. Furthermore, UV-vis spectroscopic measurements elucidate the typical green/blue color of an alpha-type cobalt hydroxide.
TL;DR: Crystallographic and spectroscopic investigations on cobalt complexes reveal that the reaction would begin with single electron transfer from an electron-rich (diphosphine)bis(trimethylsilylmethyl)cobalt(II) complex followed by reductive elimination to yield 1,2-bis(diphenylphosphino)ethane and a (d PH2) complex.
Abstract: A cobalt complex, [CoCl2(dpph)] (DPPH = [1,6-bis(diphenylphosphino)hexane]), catalyzes an intermolecular styrylation reaction of alkyl halides in the presence of Me3SiCH2MgCl in ether to yield β-alkylstyrenes. A variety of alkyl halides including alkyl chlorides can participate in the styrylation. A radical mechanism is strongly suggested for the styrylation reaction. The sequential isomerization/styrylation reactions of cyclopropylmethyl bromide and 6-bromo-1-hexene provide evidence of the radical mechanism. Crystallographic and spectroscopic investigations on cobalt complexes reveal that the reaction would begin with single electron transfer from an electron-rich (diphosphine)bis(trimethylsilylmethyl)cobalt(II) complex followed by reductive elimination to yield 1,2-bis(trimethylsilyl)ethane and a (diphosphine)cobalt(I) complex. The combination of [CoCl2(dppb)] (DPPB = [1,4-bis(diphenylphosphino)butane]) catalyst and Me3SiCH2MgCl induces intramolecular Heck-type cyclization reactions of 6-halo-1-hexenes ...
TL;DR: In this paper, a liquid phase catalytic epoxidation of styrene to styrene epoxide was carried out at 373 K using molecular oxygen at atmospheric pressure, in the presence of Co(II)-exchanged zeolite X.
TL;DR: In this article, the effects of the addition of MnO on a carbon nanofiber-supported cobalt catalyst were studied, and the results showed that MnO was associated with Co in both dried and reduced catalyst.