Cobalt oxides, higher

The alkalized zinc oxide—chromia process developed by SEHT was tested on a commercial scale between 1982 and 1987 in a renovated high pressure methanol synthesis plant in Italy. This plant produced 15,000 t/yr of methanol containing approximately 30% higher alcohols. A demonstration plant for the lEP copper—cobalt oxide process was built in China with a capacity of 670 t/yr, but other higher alcohol synthesis processes have been tested only at bench or pilot-plant scale (23). 

Other sohd cathode systems that have been widely investigated include those containing lithium cobalt oxide [12190-79-3] LiCo02 (51), vanadium pentoxide [1314-62-17, 20, and higher vanadium oxides, eg, 0 3 (52,53). 

Environmental tests have been combined with conventional electrochemical measurements by Smallen et al. [131] and by Novotny and Staud [132], The first electrochemical tests on CoCr thin-film alloys were published by Wang et al. [133]. Kobayashi et al. [134] reported electrochemical data coupled with surface analysis of anodically oxidized amorphous CoX alloys, with X = Ta, Nb, Ti or Zr. Brusic et al. [125] presented potentiodynamic polarization curves obtained on electroless CoP and sputtered Co, CoNi, CoTi, and CoCr in distilled water. The results indicate that the thin-film alloys behave similarly to the bulk materials [133], The protective film is less than 5 nm thick [127] and rich in a passivating metal oxide, such as chromium oxide [133, 134], Such an oxide forms preferentially if the Cr content in the alloy is, depending on the author, above 10% [130], 14% [131], 16% [127], or 17% [133], It is thought to stabilize the non-passivating cobalt oxides [123], Once covered by stable oxide, the alloy surface shows much higher corrosion potential and lower corrosion rate than Co, i.e. it shows more noble behavior [125]. 

Finally, Al (/= 5/2) and Co NMR spectroscopy have been used to probe AP+ in Al-doped lithium cobalt oxides and lithium nickel oxides. A Al chemical shift of 62.5 ppm was observed for the environment Al(OCo)e for an AP+ ion in the transition-metal layers, surrounded by six Co + ions. Somewhat surprisingly, this is in the typical chemical shift range expected for tetrahedral environments (ca. 60—80 ppm), but no evidence for occupancy of the tetrahedral site was obtained from X-ray diffraction and IR studies on the same materials. Substitution of the Co + by AF+ in the first cation coordination shell leads to an additive chemical shift decrease of ca. 7 ppm, and the shift of the environment A1(0A1)6 (20 ppm) seen in spectra of materials with higher A1 content is closer to that expected for octahedral Al. The spectra are consistent with a continuous solid solution involving octahedral sites randomly occupied by Al and Co. It is possible that the unusual Al shifts seen for this compound are related to the Van-Vleck susceptibility of this compound. 

Subsequent investigations were undertaken of cobalt corroles with modified structures [77] and with cobalt in higher oxidation states [78]. In addition, cobalt-containing corrole dimers were studied [79], cobalt biscorroles were investigated ]80, 81], the influence of various alkyl and aryl substituents on the electrochemical behavior of cobalt corroles was probed ]82], and the effects of solvents on the electrochemistry of these compounds was examined [83]. 

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... 

An unanticipated catalytic reaction of olefinic hydrocarbons was described in 1964 by Banks and Bailey.1 2 They discovered that C3-C8 alkenes disproportionate to homologs of higher and lower molecular weight in the presence of alumina-supported molybdenum oxide [Eq. (12.1)], cobalt oxide-molybdenum oxide, molybdenum hexacarbonyl, or tungsten hexacarbonyl at 100-200°C, under about 30 atm pressure ... 

Clark and Cook 71) disproportionated [1-14C] propylene and [2-14C] propylene over cobalt oxide-molybdate-alumina catalyst. At 60 °C their results were consistent with those reported Mol and coworkers, confirming the four-center mechanism. At temperatures above 60 °C, double-bond isomerization activity of the cobalt-molybdate catalyst became a factor and at 160 °C nearly one-half of [l-l4C] propylene had isomerized to [3-14C] propylene prior to disproportionation. The authors note that at temperatures where isomerization does not occur, the possibility of a jr-allyl intermediate appears to be excluded however, at higher temperatures, the 77-allyl mechanism cannot be so easily dismissed. 

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 ... 

The monoxides CrO, MnO, FeO, CoO, NiO are all easily oxidizable in contact with air. The higher oxides of manganese and nickel behave as the cobaltic oxide above. On the other hand, the chlorides CrCl3 and FeCU are stable, and the treatment of Fe203 and Cr203 with HC1 produces no free chlorine. 

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... 

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. 

At about 600° C. the cobalto-cobaltic oxide is reduced to cobaltous oxide, CoO, and if this is removed from the furnace and exposed to the air it becomes incandescent in consequence of re-oxidation to the higher oxide ... 

Cobaltous Oxide, Cobalt Monoxide, CoO, may be obtained from cobaltic oxide by reduction in a current of ammonia,1 or of hydrogen at about 350° C. At higher temperatures metallic cobalt is obtained. 

Additionally, the L. innocua ferritin-like protein served as a template for the controlled mineralization of two cobalt oxide phases Co(0)OH and C03O4 under two reaction temperatures of 23° and 65 °C, respectively. Substantial differences in crystallinity of the cobalt mineral core was observed between the two synthetic routes. The mineralization reaction carried out at higher temperatures yielded more crystalline nanomaterials, while the low-temperature synthesis tended toward amorphous material. The high crystallinity obtained at higher temperatures is most likely due to removal of structural waters present in the protein cavity and the surpassed energy barrier of nucleation at 65 °C. ... 

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