Design of supported cobalt catalysts with maximum activity for the Fischer-Tropsch synthesis

The role of the cobalt particle size distribution in the Fischer-Tropsch (FT) reaction for supported Co catalysts was investigated. Using TEM histogram analyses and activity measurements of carbon nanofiber-supported catalysts, the TOF of discrete Co particle sizes was calculated. It was found that cobalt particles of 4.7 ± 0.2 nm are the most active in the FT reaction (1 bar, 220 °C), and a narrow Co particle size distribution is clearly essential to arrive at the maximum activity. We have approached this requirement for maximum FT activity with an 18 wt.% Co/SiO2 catalyst prepared via impregnation, drying and calcination in NO/He. The more narrow Co particle size distribution (4.6 ± 0.8 nm) in Co/SiO2 led to an activity enhancement of ∼40% compared to Co/CNF (5.7 ± 1.4 nm), although some promoting effect of silica could not be excluded.