Nanoparticle size effects on catalyst activity and products selectivity of CNT supported cobalt catalysts in Fischer–Tropsch synthesis are studied. CNT supported cobalt catalysts prepared by two different methods (microemulsion and impregnation) are employed to yield higher hydrocarbons from synthesis gas. To achieve a series of catalysts with different Co particle size, water-tosurfactant molar ratio varied from 4 to 12. The results showed that the average particle sizes depended linearly upon the respective ratio and with decreasing the water content in microemulsion method, prepared cobalt particles to control a narrow nanoparticle size distribution with different water to surfactant ratios. The results show that cobalt-time yields increased substantially (from 3.5 to 2.9 9 10-3 mol CO/(mol(Co)s)), the site-time yields were decreased (from 26.9 to 37.0 9 10-3 s-1), C5? selectivity and chain growth probability for hydrocarbons decreased when metal particle size reduced.

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