Cobalt oxide, decomposition

Hi) Cobalt formate. There is evidence that the kinetics of decomposition of cobalt formate [1026,1027] are similar to those of the nickel salt, considered in some detail below. A significant point of difference, however, is that metal production during reaction of the former is preceded by formation of cobalt oxides [1028]. 

Thermal decomposition to cobaltous oxide, CoO, occurs at 168°C in a vacuum. 

The induction period in the oxidation of ethylbenzene catalyzed by cobalt and sodium bromide in the presence of 2,6-di-fert-butyl-p-cresol indicates that the direct initiation is negligible compared with the rate of initiation by the cobalt-catalyzed decomposition of hydroperoxide. 

The decomposition of cobalt carbonate gives cobaltous oxide, C0CO3 —> CoO + C02, but this is easily oxidizable in the air to a higher oxide. The higher oxide reacts as an oxidizing agent towards HC1 and the chloride corresponding to CoO is obtained ... 

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. 

The temperature required for the reduction of cobalt oxides to the metal appears to be somewhat higher than for the reduction of nickel oxide. The catalyst with a higher catalytic activity is obtained by reduction of cobalt hydroxide (or basic carbonate) than by reduction of the cobalt oxide obtained by calcination of cobalt nitrate, as compared in the decomposition of formic acid.91 Winans obtained good results by using a technical cobalt oxide activated by freshly calcined powdered calcium oxide in the hydrogenation of aniline at 280°C and an initial hydrogen pressure of 10 MPa (Section... 

The experiments of Rosser, Inami and Wise [57] were the continuation of their w ork on catalytic decomposition of ammonium nitrate [74]. They examined the action of copper chromite. They found that it acted at the early stage of the reaction and its action disappeared after copper diromiie was oxidized by the products of catalytic reaction. Cobalt oxide was found to be an exceptional catalyst it produced NOCl and NO2CI as major products and only a trace quantity of N2O3. Tlic authors came to the conclusion that copper chromite catalysed thermal decomposition of AP according to an electron transfer mechanism (4). 

For typical fluorous biphase catalysis the most important aspect is the simple recycling and re-use of the catalyst. Fluorous solvents have one special advantage over hydrocarbon solvents, however. Their very high oxygen dissolving capacity, combined with their extreme resistance to oxidative decomposition makes perfluorocarbons in combination with fluorous catalysts the optimum choice for oxidation reactions. Thus, the biomimetic oxidation of olefins with molecular oxygen and 2-methylpropanal as a co-reductand has been achieved with a fluorous cobalt porphyrin catalyst (22) [23], and also even without catalyst [24] (Scheme 3.7). 

Other transition metals, nickel and cobalt, also promoted gasification (Figure 14) with their activity being comparable to that of iron. Nickel was effective from the onset of the exposure to water vapour, as the hydrogen released by the oxidation was sufficient to ensure that the element was completely reduced. In contrast, cobalt oxide, formed by decomposition of the acetate with which the sample was treated, was only reduced to the elemental state on the addition of hydrogen to the gas phase such that PH2/pH20 exceeded that (0.04) at which the oxide was no longer thermodynamically stable. 

In Fig. 2, TPR profile of the unreduced dried catalyst is compared with the profile of a sample prepared from this catalyst by calcination at 500°C in air. The reduction peak at 320°C in the profile of the calcined sample may characterize the reduction of Co O /7/ while that at 470°C is caused by the reduction of mixed oxides,e.g. xCoO.yMgO.The peak at 320°C in the catalyst profile originates very probably from CO evolved during the decomposition of cobalt hydroxycarbonate (compare with Fig. 3b). The peak at 370°C may be ascribed to the reduction of cobalt oxides originating from the decomposed hydroxycarbonate. From the comparison of both TPR profiles it clearly follows that the composition of unreduced forms differs and that the metallic phase originated from different precursors. 

COBALT MURIATE (7646-79-9 7791-13-1, hexahydrate) C0CI2 Noncombustible solid. Incompatible with bases, alkali metals, ammonia vapors oxidizers, acetylene reaction may be violent. Contact with acids or acid fumes can produce highly toxic chloride fumes. Aqueous solution is a weak acid. Incompatible with metals can cause pitting attack and stress corrosion in austenitic stainless steels. Thermal decomposition releases toxic HCl, cobalt fumes, cobalt oxides. Cobalt is a known animal carcinogen. 

Fig. 2 Emission-FTIR monitoring of the decomposition of spinel cobalt oxide to cobalt monoxide in air at elevated temperatures.

The catalytic deep oxidation of methane is initiated at 250 °C and completed at 500-530 °C. It is worth noting that no methane was converted to CO2 over non-coated monoliths up a temperature of 650 °C. The performed isothermal catalytic deep oxidation at 500 °C shows a slow deactivation during the first 50 hours of time-on-stream as demonstrated in Fig. 4b. Beyond this time, the catalyst retains 80 % of its initial activity for an additional 50 hours on stream. The investigation of the deactivation process above 600 °C, not shown, indicates a strong deactivation, which was attributed to the decomposition of the spinel. The surface analysis [17] and the observed pronounced reforming activity after deactivation [21] provide evidence that deep reduction is the major cause of cobalt oxide deactivation above 600 °C. 

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