Cobalt oxide effect

Cobalt in Driers for Paints, Inks, and Varnishes. The cobalt soaps, eg, the oleate, naphthenate, resinate, Hnoleate, ethyUiexanoate, synthetic tertiary neodecanoate, and tall oils, are used to accelerate the natural drying process of unsaturated oils such as linseed oil and soybean oil. These oils are esters of unsaturated fatty acids and contain acids such as oleic, linoleic, and eleostearic. On exposure to air for several days a film of the acids convert from Hquid to soHd form by oxidative polymeri2ation. The incorporation of oil-soluble cobalt salts effects this drying process in hours instead of days. Soaps of manganese, lead, cerium, and vanadium are also used as driers, but none are as effective as cobalt (see Drying). 

It is also important to point out that pure cobalt oxide, alone or finely dispersed in Si02 (i.e. Co-Si02, Co-Si02-l and Co-Si02-2 in Table 1), zeolite HY, fullerene (i.e. C q/C-,0 80/20) is at least as effective as the reduced oxides for the production of nanotubules in our experimental conditions. In fact, the catalysts studied in this work are also active if the hydrogenation step is not performed. This important point, is presently being investigated in our laboratory in order to elucidate the nature of the active catalyst (probably a metal carbide) for the production of nanotubules. 

Li et al.22 investigated the effect of water for a platinum-promoted Co/y-Al203 catalyst during Fischer-Tropsch synthesis in a CSTR-type reactor. The catalyst lost activity in the presence of water, and it was found that small quantities of water (3-25 vol%) led to mild and reversible deactivation, whereas large amounts of water (>28 vol%) deactivated the catalyst more severely and permanently. The deactivation was attributed to the formation of cobalt oxide or cobalt aluminate. 

The early work of Bienstock ( ) at 625°F showed manganese, copper and cobalt oxides to be active. But these materials have not been used for the UltraCat Process probably because of the adverse effect on the cracking reactions. 

A true colorless glass such as an optical glass must be made with very low iron materials since decolorizing agents would reduce the transmission. The main physical decolorizers are manganese, selenium, cobalt and neodymium oxides. Manganese with a little cobalt is effective in complimenting the iron in the ferric state. 

Early in the nineties Ruiz et al. reported enhanced catalyst activities and increased selectivities to alkenes and higher hydrocarbons upon addition of V, Mg, and Ce oxides to Co-based F-T catalysts.These variations were attributed to electronic effects induced by the transition metal oxide. Similar results were obtained by Bessel et al. using a Cr promoter in Co/ZSM-5 catalysts.This group observed that the addition of Cr improved the catalyst activity, and shifted the selectivity from methane to higher, generally more olefinic, hydrocarbons. Based on H2 and CO chemisorption, as well as TPR and TPD results, they suggested that the promotion was caused by an interaction between the transition metal oxide and the cobalt oxide, which inhibits... 

The Kagome lattice structure clearly explains the non-symmetric nature of the band structure of the C0O2 layer. When the effect of the Kagome lattice becomes dominant, the bottom band, i.e., the flat band as shown in Fig, 3(a) will play a crucial role on the electronic state. Mielke [32] has shown that the flat band with the Coulomb interaction has the ferromagnetic ground state at around half filling. A prospective system for the ferromagnet will be dl transition metal oxides, i.e., the layered titanates with iso-structure of the cobalt oxides. 

Research on the important, and difficult, problem of removing small quantities of carbon monoxide from the air has shown that this can be best effected, by catalytic oxidation at room temperature, by mixtures of oxides, which are far more effective than any of the oxides singly.2 While neither manganese dioxide, silver oxide, nor copper oxide will oxidize carbon monoxide rapidly at room temperature, mixtures of manganese dioxide and copper oxide (60/40) will do so silver oxide also much accelerates the oxidation by manganese dioxide. It is stated that 1 per cent, of potash is beneficial, but larger amounts retard the oxidation. Not all oxides accelerate thus cobalt oxide retards oxidation. Various mixtures of manganese dioxide and other oxides as promoters are sold as Hopcalite. ... 

The argentic oxide catalyst may also be activated by the addition of a small amount of cobaltic oxide, CO2O3, about 0.2% of cobalt being effective for this purpose. However, cobalt activated preparations are not very stable, readily lose oxygen on storage, and absorb CO2. With... 

Many compounds, especially various metallic oxides, also induce very rapid decomposition of hydrogen peroxide without themselves being permanently changed.4 In addition to the solutions of the alkali hydroxides already,mentioned, manganese dioxide, cobalt oxide, and lead oxide (massicot) are remarkably active, and as might be expected a colloidal solution of manganese dioxide 5 is also able to exert powerful catalytic influence.6 The effect in such cases may be partly a surface effect, but is also probably due in part to the intermediate formation and decomposition of unstable highly oxidised derivatives. 

Charcoal and lampblack effect the reduction more easily than anthracite, complete reduction being effected with the former at 900° C-, some 20 to 30 per cent, of charcoal in excess of that required in the above equation being desirable. At higher temperatures the reduction proceeds much more rapidly. By briquetting the charcoal and cobalt oxide, using some organic material, such as molasses, as binder, reduction may be effected at a slightly lower temperature. 

A few compounds of cobalt and tin have been described. By fusing together at high temperatures an excess of stannic oxide and cobaltous oxide, using potassium chloride as a flux, Basic Cobalt Stannate, CoSnO,.CoO or Co2Sn04, is obtained.1 The potassium chloride is removed from the cooled mass with water, whilst warm dilute hydrochloric acid effects the solution of the stannate. The pure salt is dark green in colour density 6-30 at 18° C. 

A very recent novel hquid-phase route to hollow nanocrystals of cobalt oxide and cobalt sulfide takes advantage of the Kirkendall effect (Section 6.4.1). Injection of sulfur or oxygen into a colloidal cobalt nanocrystal dispersion created hollow nanocrystals of... 

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