Cobalt metallic, hydrogen reduction

Gas Reduction. The use of a gaseous reduciag agent is attractive because the metal is produced as a powder that can easily be separated from the solution. Carbon dioxide, sulfur dioxide, and hydrogen can be used to precipitate copper, nickel, and cobalt, but only hydrogen reduction is appHed on an iadustrial scale. In the Sherritt-Gordon process, the excess ammonia is removed duting the purification to achieve a 2 1 ratio of NH iNi ia solution. Nickel powder is then precipitated by... 

The present study revealed effects of various rutile/anatase ratios in titania on the reduction behaviors of titania-supported cobalt catalysts. It was found that the presence of rutile phase in titania could facilitate the reduction process of the orbalt catalyst. As a matter of fact, the number of reduced cobalt metal surface atoms, which is related to the overall activity during CO hydrogenation increased. 

Calciothermic reduction of samarium oxide, in the presence of cobalt powder, yields samarium-cobalt alloys in the powder form. The process is popularly known as reduction diffusion. Samarium oxide, mixed with cobalt powder and calcium hydride powder or calcium particles, is heated at 1200 °C under 1 atm hydrogen pressure to produce the alloys. Cobalt oxide sometimes partly replaces the cobalt metal in the charge for alloy preparation. This presents no difficulty because calcium can easily reduce cobalt oxide. A pelletized mixture of oxides of samarium and cobalt, cobalt and calcium, with the components taken in stoichiometric quantities, is heated at 1100-1200 °C in vacuum for 2 to 3 h. This process is called coreduction. In reduction diffusion as well as in coreduction, the metals samarium and/or cobalt form by reduction rather quickly but they need time to form the alloy by diffusion, which warrants holding the charge at the reaction temperature for 4 to 5 h. The yield of alloy in these processes ranges from 97 to 99%. Reduction diffusion is the method by which most of the 500 to 600 t of the magnetic samarium-cobalt alloy (SmCOs) are produced every year. 

Reduced cobalt accelerates the reduction of acetylene to ethane by hydrogen above 180° an. <3. some liquid paraffins result at the same time. Evidently these three metals bring about different resnlts under similar conditions. 

Cobaltous Oxide, Cobalt Monoxide, CoO, may be obtained from cobaltic oxide by reduction in a current of ammonia,1 or of hydrogen at about 350° C. At higher temperatures metallic cobalt is obtained. 

Together with Ni(CO)4 andFe(CO)5, dicobaltoctacarbonyl, Co2(CO)g (1), was among the earliest metal carbonyls (see Metal Carbonyls) to be detected and characterized by Mond and coworkers." It was prepared from frnely divided metal (or by hydrogen reduction of the oxide, CoO) in a Cu-lined autoclave made from Ni steel at 150 °C and a CO pressure of 30-40 bar. Other preparations employ reductive carbonylation of cobalt salts, mainly Co(OAc)2, or the carbonylation of an alkaline cobalt cyanide solution. The acetate salt is also the common precursor for Co2(CO)g or Co(CO)4H in the Cocatalyzed hydroformylation (see Hydroformylation) process (Section HCo(CO)4 in Hydroformylation Reactions ). 

The extraction of cobalt from arsenical concentrates consisting of autooxidation acid leaching under pressure, separation, purification, hydrogen reduction of ammoniacal leach solution, and removal of sulfur and granulation of the metal was described by Mitchell (M37). The final product contained 95.6% cobalt, 3.90% nickel, and 0.03% arsenic compared to the feed concentrate with an assay of 17.5% cobalt, 1% nickel, and 24% arsenic. 

Metals such as copper, nickel, and cobalt can be precipitated from aqueous solutions by hydrogen reduction. However this requires buffering (ammo-niacal solutions are used in the classical Sherritt-Gordon process) and high hydrogen pressures, which would be difficult to attain for most environmental applications. ... 

The cobalt metal area of the reduced perovskites was determined by hydrogen chemisorption experiments. The results are shown in Table 1. The chemisorption measurements revealed that the cobalt metallic surface area was similar for all the perovskites. This is supported by the Co/Ln surface ratio (Table I) obtained by XPS which also suggests similar metallic dispersion. The XPS analyses of the reduced perovskites showed the presence of Co" (778.6 eV) but also a doublet at approximately 780.5 and 796.2 eV which correspond to Co 2p, and Co 2p , peaks respectively, for the Co ion. Shake-up satellite lines with 4.7 eV over the Co lines were also detected indicating the presence of Co [12]. These oxidised species of cobalt are probably formed by air oxidation during the transference of the reduced sample from the reactor to the XPS spectrometer. Also, Marcos el al. [15] have shown that the reduction of the perovskite LaCoO, produced a La,0, oxide covered by hydroxyl groups which upon heating and evacuation in the XPS pretreatment chamber partly reoxidises the cobalt crystallites. 

After the copper and cobalt removal the PLS contains now almost purely NiS04(aq). The nickel can be recovered as cathodes from electrowinning or nickel powder from the hydrogen reduction In the electrowinning process, nickel is precipitated from a nickel sulphate solution into metallic form by electric current. The cathodic reaction is the reduction of nickel ions on the cathode and the anodic reaction is the oxidation of water on the surface of the lead anode. 

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