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.