Preparation of a Novel Super Active Fischer-Tropsch Cobalt Catalyst Supported on Carbon Nanotubes

Document Type : Research Article


1 Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163 Tehran, I.R. IRAN

2 Department of Chemical Engineering, University of Tehran, P.O. Box 11365-4563 Tehran, I.R. IRAN

3 Department of Chemical Engineering, University of Saskatchewan, Saskatoon, SK, S7N5C5, CANADA


The potential of carbon nanotubes (CNT) supported cobalt catalysts for Fischer-Tropsch (FT) reaction is shown. Using the wet impregnation method cobalt on carbon nanotubes catalysts were prepared with cobalt loading varying from 15 to 45 wt. %. The catalysts are characterized by different methods including: BET physisorption, X-ray diffraction, hydrogen chemisorption, and temperature-programmed reduction. The activity and product selectivity of the catalysts were assessed and compared with alumina supported cobalt catalysts using a continuous-stirred tank reactor (CSTR). Using carbon nanotubes as cobalt catalyst support was found to decrease the reduction temperature of Co3O4 to CoO from 440 to 347 oC and that of CoO to Coo from 640 to 574 oC. The strong metal-support interactions are reduced to a large extent and the reducibility of the catalysts improved by 67.7 %. CNT aided in well dispersion of metal clusters and average cobalt clusters size of the reduced cobalts is decreased from 5.3 to 4.9 nm. Results are presented showing that the hydrocarbon yield obtained by CNT supported cobalt catalyst is 74.6 % more than that obtained from cobalt on alumina supports. The maximum concentration of active surface Coo sites and FTS activity for CNT supported catalysts are achieved 40 wt. % cobalt loading. CNT caused a slight decrease in the FTS product distribution to lower molecular weight hydrocarbons.


Main Subjects

[1] Oukaci, R., Singleton, A. H., Goodwin, J. G., Comparison of Patented Co FT Catalysts Using Fixed-Bed and Slurry Bubble Column Reactors, Applied catalysis A: General, 186, 129 (1999).
[2] Iglesia,  E.,  Design,  Synthesis  and  Use  of Cobalt- Based Fischer-Tropsch Synthesis Catalysts, Applied Catalysis A: General, 161, 59 (1997).
[3] Bechara, R., Balloy, D., Vanhove, D., Catalytic Properties of Co/Al2O3 System for Hydrocarbon Synthesis, Applied Catalysis A: General, 207, 343 (2001).
[4] Steen, E. V., Prinsloo, F. F., Comparison of Preparation Methods for Carbon Nanotubes Supported Iron FT Catalysts, Catalysis  Today, 71, 327 (2002).
[5] Tavasoli,  A.,  Catalyst  Composition and its Distribution Effects on the Enhancement of Activity, Selectivity and Suppression of Deactivation Rate of FTS Cobalt Catalysts, Ph.D. Thesis, University of Tehran (2005).
[6] Tavasoli,  A., Mortazavi,  Y., Khodadadi, A., Sadagiani, K.,Effects of Different Loadings of Ru and Re on Physico-Chemical Properties and Performance of 15 % Co/Al2O3 FTS Catalysts, Iranian Journal of  Chemistry and Chemical Engineering, 35, 9 (2005).
[7] Van Berge, P.J., van de loosdrecht, J., Barradas, S., can der karaan, A. M., Oxidation of Cobalt Based Fischer-Tropsch Catalysts as a Deactivation Mechanism, Catalysis Today, 58, 321 (2000).
[8] Jacobs, G., Das, T., Zhang, Y., Li, J., Racoillet, G., Davis, B.H., Fischer-Tropsch Synthesis: Support, Loading, and Promoter Effects on the Reducibility of Cobalt Catalysts, Applied Catalysis A: General, 233, 263 (2002).
[9] Reuel, R.C., Bartholomew, C.H., Effects of Support and Dispersion on the CO Hydrogenation Activity/ Selectivity Properties of Cobalt, Journal of Catalysis, 85, 78 (1984).
[10] Bezemer, G. L., van laak, A., van Dillen, A. J., de  Jong,   K.  P.,    Cobalt   Supported    on   Carbon Nanofibers- a Promising Novel FT Catalyst, Journal of Studies In Surface Science and Catalysis, 147, 259 (2004).
 [11] Serp, P., Corrias, M., Kalck, P., Carbon Nanotubes and Nanofibers in Catalysis, Applied catalysis A: General, 253, 337(2003).
[12] Tavasoli,  A.,  Sadaghiani,  K.,  Nakhaeipour,  A., Ghalbi Ahangari, M.,Cobalt Loading Effects on the Structure and Activity for Fischer-Tropsch and Water-Gas Shift Reactions  of  Co/Al2O3  Catalysts, Iranian Journal of Chemistry and Chemical Engineering, 26, 9 (2007).
[13] Tavasoli, A., Mortazavi, Y., Khodadadi, A., Karimi, A., Accelerated Deactivation and Activity Recovery Studies of Ruthenium and Rhenium Promoted Cobalt Catalysts in Fischer-Tropsch Synthesis, Iranian Journal of Chemistry and Chemical Engineering, 36, 25 (2005).
[14] Hilmen,  A. M.,  Schanke,  D.,  Hansesen,  K. F., Holmen, A., Study of the Effect of Water on Alumina Supported Cobalt Fischer-Tropsch Catalysts, Applied Catalysis A: General, 186, 169 (1999).
[15] Zhang,  J.,  Chen,  J.,  Li, Y.,  Sun,  Y.,  Recent Technological Developments in Cobalt Catalysts for FTS, Journal of Natural Gas Chemistry, 11, 99 (2002).