Cobalt-alumina

Agrawal, P. K., Katzer, J. R., and Manogue, W. H. 1981. Methanation over transition metal catalysts. II. Carbon deactivation of cobalt/alumina in sulfur-free studies. J. Catal. 69 312-26. 

Nakamura, J., Tanaka, K., and Toyoshima, 1.1987. Reactivity of deposited carbon on cobalt-alumina catalyst. J. Catal. 108 55-62. 

Chin, R.L., and Hercules, D.M. 1982. Surface spectroscopic characterization of cobalt-alumina catalysts. J. Phys. Chem. 86 360-67. 

Das, T.K., Jacobs, G., Patterson, P.M., Conner, W.A., Li, J., and Davis, B.H. 2003. Fischer-Tropsch synthesis Characterization and catalytic properties of rhenium promoted cobalt alumina catalysts. Fuel 82 805-15. 

Wang, W.J., and Chen, Y.W. 1991. Influence of metal loading on the reducibility and hydrogenation activity of cobalt/alumina catalysts. Appl. Catal. A Gen. 77 223-33. 

Lapidus, A., Krylova, A., Kazanskii, V., Borovkov, V., and Zaitsev, A. 1991. Hydrocarbon synthesis from carbon monoxide and hydrogen on impregnated cobalt catalysts. Part I. Physico-chemical properties of 10% cobalt/alumina and 10% cobalt/ silica. Appl. Catal. 73 65-81. 

T. K. Das, G. Jacobs, P. M. Patterson, W. A. Conner, J. Li and B. H. Davis, Fischer-Tropsch synthesis characterization and catalytic properties of rhenium promoted cobalt alumina catalysts, Fuel, 2003, 82, 805-815. 

The additional comparison on Fig. 29 shows that in the coprecipitated cobalt-alumina catalyst the cobalt is altered when the catalyst is reduced in hydrogen. The change is noted in the high energy region of the spectrum. This change is receiving additional study. 

Fra. 29. Spectra of cobalt-molybdena-alumina catalyst and related compositions, C oMo04, and a coprecipitated cobalt alumina catalyst (all three samples were calcined in air) also spectrum of cobalt-alumina catalyst reduced in hydrogen. 

Fischer-Tropsch (FT) process is used for the production of hydrocarbon fuels. The process uses synthesis gases CO and H2O. It is shown that cobalt/alumina-based catalysts are highly active for the synthesis. The process is also used to convert coal to substitute or synthetic natural gas (SNG). The use of Fe-based catalysts is also believed to be attractive due to their high FT activity. HRTEM has played a major role in the study of phase transformations in Fe Fischer-Tropsch during temperature programmed reduction (TPR) using both CO and H2 (Jin et al 2000, Shroff et al 1995). TiClj/MgC -based (Ziegler-Natta) catalysts are used for polymerization of alkenes (Kim et al 2000) and EM is used to study the polymerization (Oleshko et al 2002). 

Charpenticr cl al.13 J-mm nonporous glass sphere, 3-mm poroust molybdenum cobalt alumina spheres 0.1 in 1.58 m... 

Chu, W., Chernavskii, P.A., Gengembre, L., Pankina, G.A., Fongarland, P., and Khodakov, A.Y. Cobalt species in promoted cobalt alumina-supported Fischer-Tropsch catalysts. Journal of Catalysis, 2007, 252, 215. 

Reduction. Hydrogenation of aromatic amines leads to formation of cydoalkjiamines, dicycloalkylamines, or both, depending on the reaction conditions and the type of catalyst used. Hydrogenation of aniline in the liquid phase at 25 MPa (250 atm) over a cobalt—alumina catalyst at 140°C yields cyclohexylamine [108-91-8] in 80% yield (45). Dicyclohexylamine is produced when aniline is hydrogenated in the vapor phase over a... 

Kinetic expressions similar to that of Equation 3 and similar activation energies have been reported for methanation over a cobalt-alumina catalyst (4) and for Fischer-Tropsch reaction over a cobalt-thoria catalyst (5). This similarity, despite appreciably different product distributions in the three cases, argues for a common rate-controlling step in the mechanisms. 

A number of studies have strongly suggested an effect of H2O is the oxidation of cobalt clusters for cobalt alumina catalysts, including the use of gravimetric techniques, TPD, pulse adsorption, and XPS [10-12], For the 25%Co/Al203 catalyst, the reversible effect of H2O may be due to a surface reoxidation process. The increase in CO2 selectivity (Table 9) suggests inereased WGS activity, as discussed in previous cases, potentially caused by a... 

Batista et al. performed ethanol steam reforming over cobalt/alumina and cobalt/ silica catalysts containing 8 and 18wt.% cobalt [201]. Even with a reaction temperature of400 °C, 70% conversion could be achieved. Methane was the main by-product, ethylene was only formed over samples containing 8 wt.% cobalt. Then a bed of an iron oxide/chromium oxide water-gas shift catalyst was switched behind the cobalt/ silica catalyst. The carbon monoxide was converted as expected, but also less methane was found in the product [202]. Even less carbon monoxide was formed when both catalysts were mixed. Sahoo et al. varied the cobalt content of the cobalt/alumina catalyst from 10 to 20 wt.%. The highest activity was determined for the sample containing 15 wt.% cobalt [203]. 

Kwak C, Park TJ, Sub DJ. Preferential oxidation of carbon monoxide in hydrogen-rich gas over platinnm-cobalt-alumina aerogel catalysts. Chem Eng Sci 2005 60 1211-7. 

Keywords Fischer-Tropsch, cobalt, alumina, carbon nanotube, nanoparticles... 

After reduction at 400°C, the XANES spectram (Fig. lb) displayed an intense white line, indicating a high average oxidation degree of cobalt indeed, linear fitting using a eombination of Co and CoO spectra indicated only an amount of 22% ( 3%) of metallic cobalt in the sample. This value was eorroborated by simulation of the EXAFS spectrum. In contrast to cobalt alumina catalysts, almost complete cobalt reduction to metallic phase was observed by XANES in all earbon nanotube supported samples. 

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