Showing papers on "Cobalt sulfide published in 2011"

Facile synthesis and superior supercapacitor performances of three-dimensional cobalt sulfide hierarchitectures

Abstract: Formation of three-dimensional cobalt sulfide hierarchitectures through a mechanism similar to Ostwald ripening has been investigated. Electrochemical measurements reveal that the CoS1.097nanostructure exhibits superior supercapacitor performances with high specific capacitances (555 F g−1 at 5 mA cm−2 and 464 F g−1 at 100 mA cm−2) and excellent cycle life in 2 M KOH solution.

Hydrothermal synthesis and structure evolution of hierarchical cobalt sulfide nanostructures

Abstract: Hierarchical and well-defined cobalt sulfide with flower-like, cube-like, ball-like, and surface hollowed-out nanostructures were successfully prepared by a facile one-pot hydrothermal synthesis approach, employing Co(NO3)2·6H2O as a cobalt precursor and thiourea as a sulfur source. The morphologies of these structures can be easily controlled by simply adjusting the molar ratio of reactants and solvents, reaction time, reaction temperature, and ligand types. Thiourea plays two important roles in the growth process of CoS nanostructures. First, it is decomposed to produce S2− for the final formation of CoS. On the other hand, it serves as a structure-directing agent to control the crystalline growth of CoS. The electrochemical capacitance performances of the CoS nanostructures were studied, and the flower-like CoS nanostructures show the best charge-discharge performance among all CoS products with the highest specific capacitance values of 389 F g−1 at current density of 5 mA cm−2, and 277 F g−1 at higher current density of 50 mA cm−2.

Preparation method of cobalt sulfide micro tube with hiberarchy structure

Abstract: The invention belongs to an inorganic chemical synthesis method and in particular relates to a preparation method of a cobalt sulfide micro tube with hiberarchy structure; in the invention, water-soluble cobalt salt is used as a metal source, thioacetamide is used as a sulphur source, ethanediamine is used as metal chelating agent, and cetyl trimethylammonium bromide CTAB is used as a template agent, in a closed reactor, hydro-thermal reaction is carried out under a certain temperature condition, so as to synthesize the micron tube-like cobalt sulfide with the hiberarchy structure, the outer diameter of the tube is about 1.5micron, the thickness of the tube wall is about 400nm, the average length is about 15micron, the tube wall is a nanoscale hexagonal sheet, and the length and the thickness of the sheet are 90nm and 22nm respectively; the synthesis method has the advantages of cheap and easy-obtaining raw material, simple equipment, low reaction temperature and good process repeatability and overcomes the problem of environment pollution caused by organic solvent in the previous synthesis method; the obtained product has wide application prospect in the field of biology, catalysis and material science and the like.

Preparation method of cobalt sulfide nanotubes or nanowires based on porous anodic aluminum oxide template

Abstract: The invention discloses a preparation method of cobalt sulfide nanotubes or nanowires based on a porous anodic aluminum oxide template, which comprises the following steps: producing the porous aluminum oxide template; filling cobalt chloride and thiourea solution into holes of the aluminum oxide template; adopting the step-by-step heating method to prepare the cobalt sulfide nanotubes or the nanowires; and placing the aluminum oxide template in strong base solution for etching off the aluminum oxide template, and preparing the cobalt sulfide nanotubes or the nanowires with the controllable size, wherein the nanowires or the nanotubes are placed in the holes of the aluminum oxide template The cobalt sulfide nanotubes or the nanowires have cheap raw materials, simple operation, short synthesis time and low temperature The size of the cobalt sulfide nanotubes or the nanowires and the size of the holes of the template can be controlled and adjusted The outer diameter of the holes of the cobalt sulfide nanotubes is 60-150nm, and the inner diameter is 20-80nm The diameter of the nanowires is about 60-150nm The invention relates to the method for preparing the cobalt sulfide nanotubes or the nanowires and an array thereof, which is relatively economical

COBALT(II)/NICKEL(II) COMPLEXES OF DITHIOACETYLACETONE [M(SacSac)2](M = Co, Ni) AS SINGLE SOURCE PRECURSORS FOR COBALT/NICKEL SULFIDE NANOSTRUCTURES

Abstract: Cobalt(II)/Nickel(II) complexes of 4-thiopent-3-ene-2-thione (SacSac), [M(SacSac)2](M = Co, Ni) have been used as single source precursors (SSPs) for the preparation of cobalt/nickel sulfide thin films by aerosol-assisted chemical vapor deposition (AACVD). Cobalt or nickel sulfide nanoparticles were grown by thermal decomposition of the precursor in hot trioctylphosphine oxide (TOPO) or hexadecylamine (HDA). XRD analysis showed that all samples of cobalt or nickel sulfide are of the sulfur deficient phases (Ni9S8, Co9S8, Ni7S6, or Ni3S2). SEM and TEM analysis showed that nickel sulfide formed nanowires, nanorods and spheres; cobalt sulfide formed plate like structures and spheres. The chemical compositions of the nanoparticles can be controlled by varying temperature or the capping agents.

Process for production of ferronickel smelting raw material from low grade lateritic nickel ore

Abstract: Provided is a method for producing ferronickel from a nickel sulfide or a mixed sulfide containing nickel and cobalt, obtained by hydrometallurgy of nickel oxide ore or obtained from scraps or products in process. The method for producing a ferronickel raw material is to form the ferronickel raw material from a nickel sulfide or a mixed sulfide containing nickel sulfide and cobalt sulfide, wherein treatments are performed through the following steps: (1) redissolution step, (2) deferrization step, (3) solvent extraction step, (4) hydroxylation step, (5) roasting step, and (6) washing and calcining step.

Nanoclays as nano adsorbent for oxidation of H2S into elemental sulfur

Abstract: Modified bentonites were used for the oxidation of H2S into elemental sulfur. Active phases such as iron and cobalt sulfide were added to supports Cloisite 30B and 15A. The produced nano adsorbents were characterized by X-Ray diffraction, ICP, BET surface area and SEM. Selective oxidation of H2S was carried out over the nano adsorbent in the experimental setup. The tests were performed at 70 and 180 °C, under atmospheric pressure and in the presence of 5,000 ppm of H2S in the inlet gas stream. The results confirmed the increase in the distribution of active metals and activity of Cloisite 30B, in comparison with Cloisite 15A. Cobalt-containing support showed significant improvement in the capacity of H2S removal, and in the outlet stream less than 50 ppm of H2S was detected.

Precipitation Of Nickel−Cobalt Sulfide

Abstract: Most currently operating laterite leaching plants precipitate nickel and cobalt from solution as a mixed nickel-cobalt sulfide. This sulfide typically contains 56% Ni, 5% Co, 0.5%-1% Fe, with the remaining mass made up of sulfur. The mixed nickel-cobalt precipitate is produced by contacting purified pregnant leach solution with hydrogen sulfide gas at temperatures of 80°C-120°C and partial pressures of hydrogen sulfide of between 2 and 10 bar. The recovery of the nickel and the cobalt to precipitate is approximately 99%. Rapid precipitation is promoted by recycling large quantities of product precipitate (sometimes finely ground) to the precipitation tank. This also prevents scale formation on the reactor walls, extending campaign life and minimizing maintenance costs. The mixed sulfide precipitate is an intermediate product that is re-dissolved to make concentrated solutions of nickel and cobalt suitable for high-purity metal production, which is discussed in Chapter 23 .

Method for producing raw material for ferronickel smelting from low grade nickel oxide ore

Abstract: Provided is a method for producing ferronickel from a nickel sulfide or a mixed sulfide containing nickel and cobalt, obtained by hydrometallurgy of nickel oxide ore or obtained from scraps or products in process. The method for producing a ferronickel raw material is to form the ferronickel raw material from a nickel sulfide or a mixed sulfide containing nickel sulfide and cobalt sulfide, wherein treatments are performed through the following steps: (1) redissolution step, (2) deferrization step, (3) solvent extraction step, (4) hydroxylation step, (5) roasting step, and (6) washing and calcining step.

Robust Microporous Cobalt Oxide Doped Silica Membranes for High Temperature Industrial Coal Gasification Syngas Separation

Abstract: With global demand for energy increasing alongside public concern over humanity’s potential contribution to climate change, there is a growing demand for scientific progress in cleaner power generation technologies. As wholly renewable energy technologies remain uneconomical for large scale energy delivery, this encouraged the development of more environmentally and economically sustainable processes using carbon fuels. Such technologies being pursued include advanced coal gasification power plants and emission cleaning processes for carbon dioxide capture and storage. Efficient and economical gas separation technologies are one of the major bottlenecks in the development of cleaner power production and silica membranes are currently being investigated as an alternative to the well established and energy intensive methods such as cryogenic distillation and adsorption-based systems. Silica membranes are porous, amorphous, ceramic materials that separate gases based on size exclusion and/or molecular weight difference. Within this field, several types of silica membranes have been investigated including Vycor glass membranes, chemical vapour deposition membranes, and sol-gel membranes. This thesis focuses on sol-gel silica membranes as sol-gel techniques have the advantage of being a simple and low-cost method of producing silica membranes. It is well known that pure silica membranes are hydrothermally unstable, leading to degradation of membranes in wet gas streams similar to those expected in industry. Various methods to mitigate such degradation have been investigated including the use of carbon templating and metal doping. In this thesis, cobalt was selected for incorporation into the silica matrix, both as a metal (CoSi) and as a metallic oxide (CoOxSi) and its effect on the structure, chemistry, stability and performance of resulting membranes was investigated. CoSi membranes were fabricated successfully and achieved good membrane performance characteristics as well as demonstrating the enhanced hydrothermal stability of the doped material achieving H2/N2 selectivity of 1100 at a H2 permeance of 9.5×10-8 mol•s-1•m-2•Pa-1 at 190°C under wet and re-dried conditions. Further investigation was carried out to determine the mechanism of protection provided by the cobalt dopant. The hydrothermal stability of both CoSi and CoOxSi materials were compared and it was found that CoOxSi is significantly more stable than CoSi. Study of a CoOxSi membrane under extreme hydrothermal conditions revealed that degradation still occurred, and was more pronounced at higher water feeds and temperatures, but the membrane performance stabilised over time and was still capable of significant selectivity after more than 200 hours of testing. Furthermore no significant degradation was observed with thermal cycling under hydrothermal conditions. Continuing the investigation of the stability of the material, the performance CoOxSi membranes were evaluated during exposure to trace amounts of hydrogen sulfide (H2S). H2S stability is important as it is present as a contaminant within coal gasification streams, and it is known to poison the surface of metallic Pd membranes, and many metal oxide catalysts including cobalt oxide. This investigation found no degradation attributable to exposure to H2S (at levels of up to 70ppm) at 200°C for a membrane, or at 500°C for CoOxSi xerogels. Crucially, no cobalt sulfide compounds were detected, suggesting that the cobalt oxide itself is protected by the microporous structure of the silica. In order to improve the robustness of the CoOxSi membranes as a whole, CoOxSi membranes were formed on porous steel substrates. Porous steel substrates are preferable for the commercialisation of silica membranes as they should provide the advantages of greater shock resistances and durability, in addition to reduced complexity and cost for the sealing of membranes and membrane modules into industrial unit operations. Thus an optimisation of the production process for CoOxSi membranes on porous steel substrates was undertaken for both platelet and tubular supports. It was shown that the superior chemical stability of Y2O3 stabilised ZrO2 over TiO2 as an interlayer material enabled higher quality membranes to be produced. The best results achieved were on a tubular substrate with a H2/N2 selectivity of 16.0 at a H2 permeance of 5.6×10-7 mol•s-1•m-2•Pa-1 at 450°C. Mixed gas testing at 450°C demonstrated that the membrane as a whole was stable and effective under both wet and dry gas conditions, concentrating a ~50:50 H2:N2 mixture up to 80% H2 purity. Finally to demonstrate the overall robustness of the developed CoOxSi membrane in an industrial setting, a CoOxSi membrane was tested in an operational coal fired power plant flue gas stream for 1100 hours. Post-exposure tests showed that the membrane retained an activated diffusion mechanism, and analysis of developed defects showed the presence of steel interlayer interface corrosion and fly-ash contamination, pointing to potential challenges that will need to be overcome with further research and industrial testing. Overall, this thesis explores the continual improvement and investigation of CoOxSi gas separation membrane performance in pure gases, hydrothermal conditions and trace levels of H2S contamination, and the subsequent optimisation on steel substrates, including a rare real-world stability test using an operational coal-fired power plant.

Review on Bioleaching of Nickel/Cobalt Sulfide Ore

Abstract: The bioleaching mechanism of nickel(cobalt) sulfide ore was briefly reviewed in the paper.Meanwhile,the processes and industrial application of nickel(cobalt) sulfide ore bioleaching were also introduced in recent years at home and abroad.In addition,the main research direction on bioleaching of nickel(cobalt) sulfide ore was indicated.

Solvothermal synthesis and characterization of cobalt sulfide nanocrystals

Abstract: The CoS nanocrystals were synthesized by a solvethermal method,using Co(NO3)2-6H2O and thiourea as raw materials.Composition,particle size and surface morphology of the samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results show that the as-prepared material are CoS nanoparticles at 180 ℃,witch diameter is about 40 nm.Powder production rate increases with increasing temperature,when the reaction temperature rises to 180 ℃,the yield close to 60%.When temperature further increases to 200 ℃,the yield remains unchanged,but abnormal grain growth happened.Addition of dispersant PEG can effectively control the size of the particles and inhibit the reunite of products.In additions,higher degree of crystallinity of the CoS nanocrystals can be synthesized by reducing the content of organic solvent EG,but it is not beneficial to control powder particle size,because the reaction rate is too fast.