Uses of Cobalt

About 65% of the total consumption of cobalt is for alloys and powder metallurgical (P/M) products  

Other important end products include catalysts, pigments, cobalt oxides for glass and glaze coloring and cobalt salts as fertilizers. 

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CoAsS, are also used as sources. The ore is roasted and Co is precipitated as the hydroxide and then reduced to Co with carbon (hep below 417 - C, cep to m.p.). The metal is silvery white and readily polished. It dissolves in dilute acids and is slowly oxidized in air. Adsorbs hydrogen strongly. The main use of cobalt is in alloys. Cobalt compounds are used in paints and varnishes, catalysts. Cobalt is an essential element in the diet. World production 1976 32 000 tonnes metal. 

Another market appHcation for naphthenic acid is the tire industry, where cobalt naphthenate is used as an adhesion promoter (see Adhesives Tire cords). Cobalt naphthenate improves the bonding of brass-plated steel cords to mbber, presumably by suppressing the de-zincification of brass (50). Its first reported use was in 1970 and the first patent for its use was issued in 1975 (51). About 900 t of cobalt naphthenate is used worldwide as an adhesion promoter, half of it in North America. The unit value fluctuates between 8.75—13.25 /kg because of the volatility of cobalt prices. Although it is the industry standard, the use of cobalt naphthenate is declining with the advent of more economical high metal-containing substitutes. 

Prices of cobalt compounds are directiy related to the cost of cobalt metal which fluctuates widely. Zaire is the primary cobalt suppHer. The price of cobalt metal was 46.30/kg in July 1992, down from 76.75/kg in December 1991, but up from the 27.56/kg July 1991 price. Annual usage of cobalt in the western world averaged 15,950 t in 1980—1984. The nonmetaUic uses of cobalt were about 35% in 1984 and estimated to be 40% in 1990 (1,8,9). 

Cobalt in Catalysis. Over 40% of the cobalt in nonmetaUic appHcations is used in catalysis. About 80% of those catalysts are employed in three areas (/) hydrotreating/desulfurization in combination with molybdenum for the oil and gas industry (see Sulfurremoval and recovery) (2) homogeneous catalysts used in the production of terphthaUc acid or dimethylterphthalate (see Phthalic acid and otherbenzene polycarboxylic acids) and (i) the high pressure oxo process for the production of aldehydes (qv) and alcohols (see Alcohols, higher aliphatic Alcohols, polyhydric). There are also several smaller scale uses of cobalt as oxidation and polymerization catalysts (44—46). 

Catalysts show remarkable product variation in hydrogenation of simple nitriles. Propionitrile, in neutral, nonreactive media, gives on hydrogenation over rhodium-on-carbon high yields of dipropylamine, whereas high yields of tripropylamine arise from palladium or platinum-catalyzed reductions (71). Parallel results were later found for butyronitrile (2S) and valeronitrile (74) but not for long-chain nitriles. Good yields of primary aliphatic amines can be obtained by use of cobalt, nickel, nickel boride, rhodium, or ruthenium in the presence of ammonia (4J 1,67,68,69). 

Silver-palladium-manganese brazes possess excellent creep characteristics and have been developed for high-temperature applications involving the use of cobalt or nickel-based alloys, heat-resistant steels, molybdenum and tungsten. Their liquidus temperatures lie in the range 1 100-1 250°C. 

Thickness gaging, of steel strip, 69-71 use of cobalt-60 for, 291 Thick-target x-ray spectra, 6, 7, 99-101 Thin films, thickness determined by characteristic line intensity, 153 Thin samples, analysis by x-ray emission spectrography, 167... 

Patil, V.a, Sevalkar, M.T.. Fidalikar, SV. "rhiii-layer Chiomatognphic Detection of Eo-doml n and Photphamidon by Use of Cobalt Acetate and o-lblidine , 1 C/mMnafdgr. 1990, 519. 268-270. 

Two general approaches have been used to prepare the cobalt powders. The first method(34,37,42) used 2.3 equivalents of lithium along with naphthalene as an electron carrier in DME to reduce anhydrous cobalt chloride to a dark gray powder, L Use of cobalt bromides or iodides gave a... 

Lemli and Knockaert [33] described a spectrophotometric method for the determination of miconazole nitrate suspensions and other organic bases in pharmaceutical preparations by the use of cobalt thiocyanate. The drug and the amines (as their anhydrous hydrochlorides in dichloromethane) react with solid cobalt thiocyanate to form an ion-pair complex that contains two molecules of base to one [Co(SCN)4]2. The complex is determined quantitatively by spectrophotometry versus dichloromethane at 625 nm with rectilinear response for up to 400 pg/mL of the base. This method was applied to miconazole nitrate suspensions and the coefficient of variations were generally <2%. 

Iglesia, E. 1997. Design, synthesis, and use of cobalt-based Fischer-Tropsch synthesis catalysis. Appl. Catal. 161 59-78. 

In contrast to the nickel-organozinc catalyst system, which induces /3,/3-coupling of bis(enones), the use of cobalt(ll) catalysts in the presence of silane results in a,/3-coupling to provide products of reductive Michael cyclization.48,48a,48b Both five- and six-membered ring products 26b and 25d are formed in good yields and with complete diastereoselection. The choice of silane is critical. Whereas exposure of bis(enone) 25a to Co(dpm)2... 

In contrast to rhodium and iridium, monoatomic cobalt has not been investigated extensively as a hydrosilylation catalyst, though one report discusses the use of cobalt phosphine complexes.54... 

S. J. Morris, D. Bradley, and R. Blumenthal, The use of cobalt ions as a collisionsl quencher to probe surface charge and stability of fluorescently labeled bilayer vesicles, Biochim. Biophys. Acta 818, 365-372 (1985). 

Cobalt(I) salen has been employed as a catalyst for the reduction of the following species benzal chloride [159] benzotrichloride [160] 1-bromobutane, 1-iodobutane, and 1,2-dibromobutane [161] iodoethane [162], benzyl chloride [163], and ethyl chloroacetate [164]. Rusling and coworkers have investigated the use of cobalt(I) salen, as well as vitamin Bi2s and cobalt(I) phthalocyanine, in both homogeneous phase and bicontin-uous microemulsions for the catalytic reduction of vicinal dibromides [165] and... 

With an annual production of up to 9.3 million tons in 1998, hydroformylation is the most important homogeneously catalyzed reaction [20,21], The reaction is performed almost exclusively by the use of cobalt or rhodium catalysts. The advantages of rhodium catalysts are milder reaction conditions and better n/iso ratios in product distribution. The toxicity of rhodium compounds as well as the high rhodium price [22] (between 20 and 75 g during the last five years) demand an efficient catalyst recycling. 

These results promote a potential use of cobalt catalysts instead of expensive rhodium-based catalysts for the hydroformylation in SCCO2 [16,17,209, 210]. Although the main goal of this study was to demonstrate catalyst recycling, it must be noted that the catalytic performances have been obtained at process parameters and imder conditions that were far from being optimized. 

Combined use of cobalt(II) acetylacetonate [Co(acac)2] and DiBAlH also gives selective... 

The most imporant use of cobalt is in the manufacture of various wear-resistant and superalloys. Its alloys have shown high resistance to corrosion and oxidation at high temperatures. They are used in machine components. Also, certain alloys are used in desulfurization and hquefaction of coal and hydrocracking of crude oil shale. Cobalt catalysts are used in many industrial processes. Several cobalt salts have wide commercial apphcations (see individual salts). Cobalt oxide is used in glass to impart pink or blue color. Radioactive cobalt-60 is used in radiography and sterihzation of food. 

Fischer-Tropsch synthesis making use of cobalt-based catalysts is a hotly persued scientific topic in the catalysis community since it offers an interesting and economically viable route for the conversion of e.g. natural gas to sulphur-free diesel fuels. As a result, major oil companies have recently announced to implement this technology and major investments are under way to build large Fischer-Tropsch plants based on cobalt-based catalysts in e.g. Qatar. Promoters have shown to be crucial to alter the catalytic properties of these catalyst systems in a positive way. For this reason, almost every chemical element of the periodic table has been evaluated in the open literature for its potential beneficial effects on the activity, selectivity and stability of supported cobalt nanoparticles. 

Aryl- or heteroarylzinc species have been successfully synthesized from the corresponding aryl or heteroaryl bromides or chlorides in high yields, on the laboratory scale (10 mmoles of substrate). The use of cobalt as catalyst allowed the synthesis of organozinc reagents using the sacrificial anode process with a wide variety of solvents. 

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