Spinels cobaltate

Figure 2 X-ray diffractogram of the inverse spinel cobalt ferrite CoFejO,. ...

Chemical vapor deposition (CVD) was applied to produce homogeneous thin films of pure and doped spinel cobalt oxide with similar morphology on the surface of planar and monolithic supports. The planar substrates were used to investigate the thermal stability and the redox properties of the spinel using temperature-programmed methods monitored by emission-FTIR spectroscopy, while the monolithic substrates were used to test the catalytic performance of the deposited films toward the deep oxidation of methane and to evaluate its durability. The high performance of cobalt oxide to oxidize methane in diluted streams was demonstrated at 500 °C. Furthermore, controlled doping of cobalt oxide layers with suitable cations was demonstrated for nickel as an example, which resulted in substantial increase of electric conductivity. 

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

Cobalt ahiminate blue Cobalt aluminate blue spinel Cobalt aluminate spinel. See Cobalt aluminum oxide... 

Cobalt aluminate spinel Cobalt blue Pigment blue 28 Thenard s blue Empirical AI2C0O,... 

Naveen, A. N., and S. SeUadurai. 2014. Investigation on physiochemical properties of Mn substituted spinel cobalt oxide for supercapacitor applications. Electrochimica Acta 125 404-414. 

Rinmann s green, ZnCojO. A spinel formed when cobalt nitrate solution is placed on zinc oxide and the mixture heated to redness. The green colour forms a delicate test for Zn. 

Sillimanite, see Aluminum silicon oxide (1/1) Smithsonite, see Zinc carbonate Soda ash, see Sodium carbonate Spelter, see Zinc metal Sphalerite, see Zinc sulflde Spherocobaltite, see Cobalt(II) carbonate Spinel, see Magnesium aluminate(2—)... 

The predominant process for manufacture of aniline is the catalytic reduction of nitroben2ene [98-95-3] ixh. hydrogen. The reduction is carried out in the vapor phase (50—55) or Hquid phase (56—60). A fixed-bed reactor is commonly used for the vapor-phase process and the reactor is operated under pressure. A number of catalysts have been cited and include copper, copper on siHca, copper oxide, sulfides of nickel, molybdenum, tungsten, and palladium—vanadium on alumina or Htbium—aluminum spinels. Catalysts cited for the Hquid-phase processes include nickel, copper or cobalt supported on a suitable inert carrier, and palladium or platinum or their mixtures supported on carbon. 

Good results are obtained with oxide-coated valve metals as anode materials. These electrically conducting ceramic coatings of p-conducting spinel-ferrite (e.g., cobalt, nickel and lithium ferrites) have very low consumption rates. Lithium ferrite has proved particularly effective because it possesses excellent adhesion on titanium and niobium [26]. In addition, doping the perovskite structure with monovalent lithium ions provides good electrical conductivity for anodic reactions. Anodes produced in this way are distributed under the trade name Lida [27]. The consumption rate in seawater is given as 10 g A ar and in fresh water is... 

Nickel sulfides are very similar to those of cobalt, consisting of NiS2 (pyrites structure, p. 680), Ni3S4 (spinel structure, p. 247), and the black, nickel-deficient Nii-j S (NiAs structure, p. 555), which is precipitated from aqueous... 

It is worthwhile to point out that lithium extraction from inverse spinels V[LiM]04, such as V[LiNi]04 and V[LiCo]04 takes place at high voltage, typically between 4 and 5V [153]. Lithium is extracted from the octahedral 16d sites of these spinels with a concomitant oxidation of the divalent nickel or cobalt ions. From a structural point of view, this can be readily understood because lithium must be dislodged from the 16d octahedral sites, which are of low-energy, into neighboring energetically unfavorable 8b tetrahedra, which share all four faces with 16d sites that are occupied by nickel or cobalt and by lithium. Lithium extraction reactions... 

Many late transition metals such as Pd, Pt, Ru, Rh, and Ir can be used as catalysts for steam reforming, but nickel-based catalysts are, economically, the most feasible. More reactive metals such as iron and cobalt are in principle active but they oxidize easily under process conditions. Ruthenium, rhodium and other noble metals are more active than nickel, but are less attractive due to their costs. A typical catalyst consists of relatively large Ni particles dispersed on an AI2O3 or an AlMg04 spinel. The active metal area is relatively low, of the order of only a few m g . ... 

We distinguish electrodes consisting of simple oxides, from those consisting of complex oxide systems. The latter include cations of different metals or cations of a given metal in different valence states. An example for the latter type is cobalt cobaltite C03O4 (a spinel structure) containing Co and Co ions. 

Cobaltites with spinel stractnre have compositions MC02O4, where M is a metal forming divalent cations, snch as zinc, cadminm, magnesinm, nickel, manganese, and divalent cobalt. In contrast to the perovskites, the cobaltites have a rather high catalytic activity already at room temperatnre. Experiments show that the activity increases with increasing spinel structure content (i.e., increasing number of Co ions) of the catalyst snrface. The trivalent cobalt ions promote the withdrawal of... 

It is interesting to note that cobalt cobaltite, C03O4, is a good catalyst, too, for anodic chlorine evolution. In this case, too, a correlation is observed between the reaction rate and the spinel s defect concentration (amount of nonstoichiometric oxygen). 

Only two oxides of cobalt have been characterized, CoO and Co304 (which is actually ConConl04). The latter has a structure in which Co2+ ions are located in tetrahedral holes and Co3+ ions are located in octahedral holes of a spinel structure. Decomposition of either Co(OH)2 or CoC03 produces CoO, and decomposition of Co(N03)2 can be used to produce Co304. 

Soled S.L., Iglesia E., and Fiato R.A. 1992. Copper-promoted cobalt manganese spinel catalyst and method for making the catalyst for Fischer-Tropsch synthesis. U.S. Patent 5162284. 

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