Modeling the Fischer-Tropsch Reaction In a Slurry Bubble Column Reactor

Authors: F. Gholami, M. Torabi Angaji, Z. Gholami

Abstract:

Fischer-Tropsch synthesis is one of the most important catalytic reactions that convert the synthetic gas to light and heavy hydrocarbons. One of the main issues is selecting the type of reactor. The slurry bubble reactor is suitable choice for Fischer- Tropsch synthesis because of its good qualification to transfer heat and mass, high durability of catalyst, low cost maintenance and repair. The more common catalysts for Fischer-Tropsch synthesis are Iron-based and Cobalt-based catalysts, the advantage of these catalysts on each other depends on which type of hydrocarbons we desire to produce. In this study, Fischer-Tropsch synthesis is modeled with Iron and Cobalt catalysts in a slurry bubble reactor considering mass and momentum balance and the hydrodynamic relations effect on the reactor behavior. Profiles of reactant conversion and reactant concentration in gas and liquid phases were determined as the functions of residence time in the reactor. The effects of temperature, pressure, liquid velocity, reactor diameter, catalyst diameter, gasliquid and liquid-solid mass transfer coefficients and kinetic coefficients on the reactant conversion have been studied. With 5% increase of liquid velocity (with Iron catalyst), H2 conversions increase about 6% and CO conversion increase about 4%, With 8% increase of liquid velocity (with Cobalt catalyst), H2 conversions increase about 26% and CO conversion increase about 4%. With 20% increase of gas-liquid mass transfer coefficient (with Iron catalyst), H2 conversions increase about 12% and CO conversion increase about 10% and with Cobalt catalyst H2 conversions increase about 10% and CO conversion increase about 6%. Results show that the process is sensitive to gas-liquid mass transfer coefficient and optimum condition operation occurs in maximum possible liquid velocity. This velocity must be more than minimum fluidization velocity and less than terminal velocity in such a way that avoid catalysts particles from leaving the fluidized bed.

Keywords: Modeling, Fischer-Tropsch Synthesis, Slurry Bubble Column Reactor.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1333730

References:

[1] Jordan, R. B. (1991). Reaction Mechanism of Inorganic and Organometallic System, Ch. 5, Oxford University Press, New York.
[2] N. Rados, M.H. Al-dahhan, M.P. Dudukovic, (2003), Modeling of the Fischer-Tropsch synthesis in slurry bubble column reactors, Catal. Today 79-80 211-218.
[3] R. Krishna (1999), Fundamentals and Selection of Advanced Fischer- Tropsch Reactors, Applied Catalysis A: General 186 55-70.
[4] C.Maretto, R. Krishna (1999), Modeling of a Bubble Column Slutty Reactor for Fischer-Tropsch Synthesis, Catalysis Today 52 279-289.
[5] Huang, S.H., Lin, H.M.,and chao,K.C.(1987). Fluid Phase Equilibria,36,141.
[6] Roper,M. (1983). Fischer-Tropsch Synthesis,W.Keim,D.Reidel Publishing.Boston.
[7] M.E. Dry, Advances in Fischer-Tropsch Chemistry, Ind. Eng. Chem.Prod. Res. Dev., 15(1976)282-286.
[8] W.D. Deckwer, Y, Serpemen,M..Ralek, B. Schmidt, (1982). Modeling the Fischer-Tropsch Syntrheis in the Slurry Phase, Ind. Eng. Chem. Prod. Res. Dev.21 231-241.
[9] I.C. Yates, C.N. Satterfield, (1991). Energy Fuels 5 168-173.
[10] E.Costa, A. De Lucas, P. Garcia (1986) , Fluid Dynamics of Gas-Liquid- Solid Fluidized Beds, Ind. Eng. Chem. Prod. Res. Dev. 25 849-854.
[11] Saxena, S. C. (1995). Catal. Rev.-Sci. Eng.,37(2), 227.
[12] Kunii, D. and Levenspiel,O. (1991). Fluidization Eng., Butterworth,Boston.
[13] Han, J. H., Wild, G., and Kim, S. D. (1990). Chem. Eng. J., 43, 67.
[14] Bloxom, V. R., Costa, J. M., Herranz, J., MacWilliam, G. L., and Roth, S. R. (1975). Determination and Correlation of Hydrodynamic Variables in a Tree-Phase Fluidized Bed (Part IV), In: Report No. 219, Oak Ridge National Laboratory- MIT.
[15] Fair, J. R. (1967). Chem. Eng., 74,76.
[16] Soong, Y.,Harke, F. W., Gamwo, I. K., Schehl, R. R., and Zarochak, M. F. (1997). Catal. Today, 35, 427.
[17] S. A. Hedrick, S.S. Chuang, Modeling the Fischer-Tropsch Reaction in a Slurry Bubble Column Reactor, Chemical Engineering Communications. 2003, 190, 445-474.
[18] S. T. Sie Shah, Y., T., Dassori, C. G., and Tierney, J. W. (1990). Chem. Eng. Comm., 88,49.