Abstract: The unity bond index-quadratic exponential potential (UBI-QEP) model is used to evaluate the heat of chemisorption of adsorbed species and activation barriers for the elementary reactions in the mechanisms for Fischer-Tropsch synthesis (FTS) reaction over a model catalyst Co(0001), including carbide mechanism, hydroxycarbene mechanism, and CO insertion mechanism. It is demonstrated that the reaction pathway for the formation of hydrocarbons proposed in the carbide mechanism is energetically favorable. The insertion of CO is the pathway for the formation of oxygenations. Dissociation of adsorbed CO and hydrogenation of C_ads have higher activation barriers than other elementary steps in the reaction pathway. The energetically preferred pathway to initiate the carbon chain growth is via insertion of CH_{2, ads} intermediate into the carbon-metal bond of CH_{3, ads} or CH_{2, ads} group. The activation barrier for termination of carbon chain propagation by β-H elimination is lower than hydrogenation. The olefins and oxygenates in the primary products during FTS are apt to conduct the secondary reaction via readsorption on the catalyst surface because of its low active energies. Compared with Fe/W(110), the activation barriers for CH_{x, ads} hydrogenations and CH_{2, ads} insertion are lower on Co(0001), which results in higher selectivity of methane and more yield of heavy hydrocarbons.

Key words: Fischer-Tropsch synthesis, Co(0001) single crystal surface, UBI-QEP model, Reaction mechanism