Cobalt chemical processing

Production of cobalt in general is based on various physical and chemical processes that include magnetic separation (for arsenic sufide ores), sulfatiz-ing roasting (for sulfide ores), ammoniacal leaching, catalytic reduction, and electrolysis. 

The CHEMIC process is effective in removing cadminm, mercnry, lead, iron uranium, strontium, cesium, and cobalt. The process also removes other inorganic and organic materials present as suspended or colloidal solids. 

In the chemical process industries, nickel, cobalt, platinum, palladium, and mixtures containing potassium, chromium, copper, aluminum, and other metals are used in very large-scale dehydrogenation processes. For example, acetone (6 billion pounds per year) is made from isopropyl alcohol styrene (over 2 billion pounds per year) is made from ethylbenzene. The dehydrogenation of n-paraffins yields detergent alkylates and n-olefins. The catalytic use of rhenium for selective dehydrogenation has increased in recent years. Dehydrogenation is one of the most commonly practiced of ihe chemical unit processes. 

In the chemical process industries, nickel, cobalt, platinum, palladium, and mixtures containing potassium, chromium, copper, aluminum, and other metals are used in very large-scale dehydrogenation processes. 

The industrial scale procedure probably most important for synthesis of per-fluorocarbon-based solvents was developed during the Manhattan Project [12] (Figure 2.2). In the so-called cobalt trifluoride process (recently commercialized by F2 Chemicals as the Flutec process) [13] the large fluorination enthalpy is harnessed by dividing the reaction into two less exothermic steps. In the first step, CoFj is oxidized with fluorine, at 350 °C, to CoFj. In the second step, the organic... 

Figure 2.2 Schematic representation of the apparatus used to perform the cobalt trifluoride process (courtesy of the American Chemical Society) [13].

The commercial process for the production of nylon 6 starts with the oxidation of cyclohexane with oxygen at 160°C to a mixture of cyclohexanol and cyclohexanone with a cobalt(II) catalyst. The reaction is taken to only 4% conversion to obtain 85% selectivity. Barton and co-workers have called this the least efficient major industrial chemical process.240 They have oxidized cyclohexane to the same products using tort bu(ylhydroperoxide with an iron(III) catalyst under air (70°C for 24 h) with 89% efficiency based on the hydroperoxide. The oxidation of cyclohexanol to cyclohexanone was carried out in the same way with 99% efficiency. A cobalt catalyst in MCM-41 zeolite gave 38% conversion with 95% selectivity in 4 days at 70 C.241 These produce ferf-butyl alcohol as a coproduct. It can be dehydrated to isobutene, which can be hydro-... 

Preparation of mixed metal oxide precursors for SOFCs represents a very complex chemical process in which a metal may form oxides, hydroxides, and various complex basic salts as intermediates. Understanding of the relationship between the calcination process, the final composition, particle sizes, sinterability, and SOFC performance for nickel, copper and cobalt-based anode materials is a necessity [26]. 

Among the lefiactory carbides and nitrides, tungsten carbide with a cobalt binder is the most important material used widely in the coating of gas-turbine components for aircraft and industrial use, components of steam turbines and diesel engines, components for the oil and gas industry, paper and pulp industry, and chemical processing industry (see Ch. 16). 

A wide variety of metals is produced for industries such as automotive, aerospace, marine, energy, chemical processing, etc. Materials include aluminum, titanium, stainless steel, nickel- and cobalt-base alloys, tool steels, and materials for electronic, magnetic, and expansion applications. Regardless of the metal, the stime selection process can be used. 

Radioactive sources are used for medical treatment of cancer (cobalt 60), for industrial X-rays of metal components, for thickness gauges, for chemical process control, and to anti-static plastic sheet. Radioactive isotopes are used in chemical tracer anafysis , while X-rays are also used medicalfy for diagnosis. 

The final PBT-TRI rule did not change the TRI reporting requirements for cobalt. Vanadium compounds were added to the list of TRI reportable substances. Reporting thresholds are the same as other substances, 10 000 pounds for chemicals processed or otherwise used or 25 000 pounds for manufactured compounds. 

Chemical ingenuity in using the properties of the elements and their compounds has allowed analyses to be carried out by processes analogous to the generation of hydrides. Osmium tetroxide is very volatile and can be formed easily by oxidation of osmium compounds. Some metals form volatile acetylacetonates (acac), such as iron, zinc, cobalt, chromium, and manganese (Figure 15.4). Iodides can be oxidized easily to iodine (another volatile element in itself), and carbonates or bicarbonates can be examined as COj after reaction with acid. 

Reduction. Hydrogenation of dimethyl adipate over Raney-promoted copper chromite at 200°C and 10 MPa produces 1,6-hexanediol [629-11-8], an important chemical intermediate (32). Promoted cobalt catalysts (33) and nickel catalysts (34) are examples of other patented processes for this reaction. An eadier process, which is no longer in use, for the manufacture of the 1,6-hexanediamine from adipic acid involved hydrogenation of the acid (as its ester) to the diol, followed by ammonolysis to the diamine (35). 

Rhodium Ca.ta.lysts. Rhodium carbonyl catalysts for olefin hydroformylation are more active than cobalt carbonyls and can be appHed at lower temperatures and pressures (14). Rhodium hydrocarbonyl [75506-18-2] HRh(CO)4, results in lower -butyraldehyde [123-72-8] to isobutyraldehyde [78-84-2] ratios from propylene [115-07-17, C H, than does cobalt hydrocarbonyl, ie, 50/50 vs 80/20. Ligand-modified rhodium catalysts, HRh(CO)2L2 or HRh(CO)L2, afford /iso-ratios as high as 92/8 the ligand is generally a tertiary phosphine. The rhodium catalyst process was developed joindy by Union Carbide Chemicals, Johnson-Matthey, and Davy Powergas and has been Hcensed to several companies. It is particulady suited to propylene conversion to -butyraldehyde for 2-ethylhexanol production in that by-product isobutyraldehyde is minimized. 

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