Cottenier, Stefaan

Filot, Ivo

Joos, Lennart

van Santen, Rutger A

Van Speybroeck, Veronique

Waroquier, Michel

English

Ghent University Academic Bibliography

Reactivity of CO on clean and carbon covered cobalt surfaces in Fischer-Tropsch synthesis  Lennart Joos a,Ivo Filot b, Michel Waroquier a, Stefaan Cottenier a,Veronique Van Speybroeck a, Rutger van Santen b  a Center for Molecular Modeling, Ghent University, Technologiepark 903, 9052 Zwijnaarde, Belgium b Molecular Heterogeneous Catalysis, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands  The increasing demand for liquid transportation fuels on the one hand, and the high prices for petroleum oil on the other, raised the interest for alternative hydrocarbon feedstock, such as natural gas, biomass and coal. In the promising Gas-To-Liquid process, Fischer-Tropsch Synthesis (FTS) is used to convert syngas (a mixture of CO and H2) to long-chain hydrocarbons on a cobalt catalyst.   Different mechanisms deactivate the cobalt  surface during FTS[1]. Carbon deposition is one of the main deactivation mechanisms but is extremely difficult to observe experimentally, due to the presence of wax-like hydrocarbons on the surface and in the pores of the catalyst. Understanding the deactivation mechanism at a molecular level is crucial for developing efficient cobalt-based FTS catalysts with high activity, selectivity and stability.    In our computational study, the influence of carbon deposits on CO adsorption and dissociation on  cobalt is modeled. CO dissociation is taken as a model reaction as it is the first step in the carbene mechanism and has to proceed fast enough in order to produce long carbon chains[2]. Both on-surface and subsurface carbon species are considered and both the Co(0001) and the Co(1  21) surface are taken into account. Studying two surface allows us to investigate the influence of the topology of the active site[3].  Our calculations show that carbon species increase the reaction barrier and energy for CO dissociation. The reaction is slowed down and is also thermodynamically less likely to proceed. The subsurface carbon species have the largest influence. We conclude that carbon deposition is indeed a significant mechanism for deactivation. It is thus necessary to keep carbon fouling under control in industrial reactors.   E-mail:  lennart.joos@ugent.be www: http://molmod.ugent.be/  [1] A. M. Saib, D. J. Moodley, I. M. Ciobica, M. M. Hauman, B. H. Sigwebela, C. J. Weststrate, J. W. Niemantsverdriet, J. van de Loosdrecht, Catalysis Today 2010, 154, 271. [2] S. Shetty, R. A. van Santen, Catalysis Today 2011, 171, 168. [3] Q. F. Ge, M. Neurock, Journal of Physical Chemistry B 2006, 110, 15368.   

Reactivity of CO on clean and carbon covered cobalt surfaces in Fischer-Tropsch synthesis

https://biblio.ugent.be/publication/2062303/file/2062311

Reactivity of CO on clean and carbon covered cobalt surfaces in Fischer-Tropsch synthesis

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Ghent University Academic Bibliography