Cobalt catalyst for Fischer-Tropsch

Bezemer, G. L., Radstake, P. B., Falke, U., Oosterbeek, H., Kuipers, H. P. C. E., van Dillen, A., and de Jong, K. P. 2006. Investigation of promoter effects of manganese oxide on carbon nanofiber-supported cobalt catalysts for Fischer-Tropsch synthesis. Journal of Catalysis 237 152-61. 

Yu, Z., Borg, 0., Chen, D., Enger, B. C., Frpseth, V., Rytter, E., Wigum, H., and Holmen, A. 2006. Carbon nanofiber supported cobalt catalysts for Fischer-Tropsch synthesis with high activity and selectivity. Catalysis Letters 109 43 -7. 

Tsubaki, N., Sun, S., and Fujimoto, K. 2001. Different functions of the novel metals added to cobalt catalysts for Fischer-Tropsch synthesis. J. Catal. 199 236 -6. 

Zhang, Y., Shinoda, M., and Tsubaki, N. 2004. Development of bimodal cobalt catalysts for Fischer-Tropsch synthesis. Catal. Today 93 55-63. 

Dalai et al.31 investigated the effect of water on the performance of narrow and wide-pore silica-supported cobalt catalysts for Fischer-Tropsch synthesis. Three catalysts were studied 12.4 wt% Co on a wide-pore silica, 20 wt% Co on a... 

We now encounter a semantic problem of considerable size. It has been recognised for a very long time that the activity of metal catalysts can be helped by the presence of quite small amounts of substances that of themselves have no or little activity. This concept first achieved prominence in the development of iron catalysts for ammonia catalysts, and of iron and cobalt catalysts for Fischer-Tropsch synthesis, and the term promoter was applied to these substances. They were of two kinds (i) structural promoters such as alumina, which acted as grain stabilisers and prevented metal particle sintering and (ii) electronic promoters such as potassium that entered the metallic phase and actually enhanced its activity. In these cases the metal is the major component, so that the catalyst is a promoted metal rather than a supported metal. 

Mittasch as central one developed Zn0/Cr203 catalysts for methanol synthesis and Cobalt catalyst for Fischer-Tropsch synthesis. 

W. Chu, L. Wang, P.A. Chemavskii, A.Y. Khodakov, 2008, Glow-discharge plasma-assisted design of cobalt catalysts for Fischer-Tropsch synthesis, Angew. Chem. Int. Ed., 47,5052-5055. 

Several studies [4, 5] have shown that the activity of cobalt catalysts for Fischer-Tropsch synthesis is structure-insensitive the number of active sites depends on the cobalt particle size, loading amount and reduction degree. Also, it is known that the catalyst performance can be significantly increased by cobalt dispersions at the particle range of 3-5 run [4]. It is thus very important to control the metal size particle. However, cobalt crystallites dispersions above 5-6 nm are difficult to prepare [4], The present work, focuses on the detailed investigation of the stracture of cobalt nanoparticles on aliunina and caibon nanotubes, prepared by a simple and fast method, to be used in Fischer-Tropsch synthesis. 

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. 

Zhan, X., Arcuri, K., Huang, R., Agee, K., Engman, J., and Robota, H. J. 2004. Regeneration of cobalt-based slurry catalysts for Fischer-Tropsch synthesis. Prep. Pap.-Am. Chem. Soc. Div. Pet. Chem. 49 179-81. 

Mossbauer spectroscopy is one of the techniques that is relatively little used in catalysis. Nevertheless, it has yielded very useful information on a number of important catalysts, such as the iron catalyst for Fischer-Tropsch and ammonia synthesis, and the cobalt-molybdenum catalyst for hydrodesulfurization reactions. The technique is limited to those elements that exhibit the Mossbauer effect. Iron, tin, iridium, ruthenium, antimony, platinum and gold are the ones relevant for catalysis. Through the Mossbauer effect in iron, one can also obtain information on the state of cobalt. Mossbauer spectroscopy provides valuable information on oxidation states, magnetic fields, lattice symmetry and lattice vibrations. Several books on Mossbauer spectroscopy [1-3] and reviews on the application of the technique on catalysts [4—8] are available. 

W. Yang, H. Gao, H. Xiang, D. Yin, Y. Yang, J. Yang, Y. Xu, and Y. Li, Cobalt supported mesoporous silica catalyst for Fischer-Tropsch synthesis, Acta Chim. Sinica 59, 1870-1877 (2001). 

Figure 6.18 illustrates the technique with a study on a proprietary cobalt on alumina Tropsch catalyst for Fischer-Tropsch synthesis (the reaction of synthesis gas, CO + Fl2, to hydrocarbon fuels) [55]. Trace amounts of platinum help to obtain an appreciable degree of reduction for the cobalt (similarly as in the temperature-programmed reduction of bimetallic Fe-Rh catalysts in Fig. 2.4). The left part of Figure 6.18 shows Co K-edge XANES of metal and oxide reference compounds, and illustrates the strong intensity of the white line region for ionic cobalt compounds. The XANES spectrum of the calcined CoPt/A Ch catalyst re-...

The activities of the cobalt supported catalyst for Fischer-Tropsch synthesis are summarised in Fig. 2 in terms of yields of Cj to C3 hydrocarbons. Only data at 250°C and 325°C are presented although other temperatures have been examined. The cobalt on IfeO, on the zeolite support, and on the blank supports alone, were inactive. The same groupings occurred with respect to CO consumption in the TPC runs. 250° C... 

Fig. 2. Activity of various cobalt supported catalysts for Fischer-Tropsch synthesis at 25 and 325°C.

Xing C, Yang G, Wang D, Zeng C, Jin Y, Yang R, Suehiro Y, Tsubaki N. Controllable encapsulation of cobalt clusters inside carbon nanombes as effective catalysts for Fischer-Tropsch synthesis. Catal Today 2013 215 24-8. 

Cobalt nanoparticles on alumina and caibon nanotube with a with thin-plate shape from 3 to 5 nm, in small clusters of 10 to 20 nm, were successfully prepared and characterized using a wide ragne of techniques. Theier strcture, morphology and reduction behavior depend on the support. These solids have suitable characteristics which make them potential candidates as catalysts for Fischer-Tropsch reaction. 

Ellis PR. and Bishop P.T. 2006. Supported cobalt catalysts for the Fischer-Tropsch synthesis. International Patent Application WO2006/136863. 

Iglesia, E., Soled, S. L., Baumgartner, J. E., and Reyes, S. C. 1995. Synthesis and catalytic properties of eggshell cobalt catalysts for the Fischer-Tropsch synthesis. J. Catal. 153 108-22. 

Jacobs, G., Das, T.K., Li, J., Luo, M., Patterson, P.M., and B.H. Davis. 2007. Fischer-Tropsch synthesis Influence of support on the impact of co-fed water for cobalt-based catalysts. In Fischer-Tropsch synthesis Catalysts and catalysis, ed. B.H. Davis and M.L. Occelli, 217-53 Amsterdam, The Netherlands Elsevier. 

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 decomposition of bulk formates has drawn special attention, in connection with the function of promoters in iron and cobalt catalysts for the Fischer-Tropsch synthesis. In the investigations made on this point the interest was, naturally, focused on the organic products formed during the decomposition of the formate [Hofmann and Schibsted (53), Marec and Hahn (126)]. 

A controversial issue related to cobalt catalysts in Fisher-Tropsch synthesis is the structure-sensitive character of this reaction. Iglesia and co-workers [126,127] reported a large increase in activity when the cobalt particle size was decreased from 200 nm to 9 nm, whereas the specific activity [turnover frequency (TOF)] was not influenced by the cobalt particle size. However, other authors have reported that the TOF suddenly decreased for catalysts with cobalt particle sizes smaller than 10 nm [122,128]. Bezemer et al. [125] were the first to investigate the influence of cobalt particle size in the range 2.6 to 27 nm on performance in Fischer-Tropsch synthesis on well-defined catalysts supported on carbon nanofibers. It was found that the TOF for CO hydrogenation was independent of cobalt particle size for catalysts with particles larger then 6 nm (at atmospheric pressure) or 8 nm (at 35 bar). But both the TOF and the C5+ selectivity decreased for catalysts with smaller particles. It was proposed that the cobalt particle size effects could be attributed to a strucmre-sensitivity characteristic of the reaction, together with a CO-indnced reconstmction of the cobalt surface. 

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