Abstract: The Mnmodified cobalt catalysts for FischerTropsch(FT) synthesis were characterized and tested by TPR, H2TPD, FTIR, and CO hydrogenation. It was found that a suitable addition of manganese could improve the catalytic activity and selectivity and suppress the methane and C24 hydrocarbons. XRD and FTIR results showed that the presence of Mn could improve the dispersion of active phases and favor the formation of bridgedtype adsorbed CO. A small amount of Mn could increase the uptake of hydrogen, but excess of manganese might decrease the uptake of hydrogen. Such a shift of the reaction performances was related to the change of adsorbed CO species.

Key words: Foscjer-Tropsch(F-T) synthesis, Co/Al₂O₃ catalysts, Mn promoter, Supporter, Characterization