Influence of Ru segregation on the activity of Ru–Co/γ-Al2O3 during FT synthesis: A comparison with that of Ru–Co/SiO2 catalysts

γ-Al2O3 and SiO2 supported Co catalysts, with varying amounts of Ru, were prepared and evaluated for Fischer–Tropsch synthesis (FTS). The composition of Ru for optimum activity was found to be support-dependent. The reducible Co3O4 was high in the region of 0–1.64 wt.% of Ru in Co/SiO2 catalysts. Co/γ-Al2O3 displayed a maximum for reducible Co species at 0.42 wt.% Ru. Segregation of Ru occurred beyond this composition decreasing the extent of reduction. Co/γ-Al2O3 catalysts showed lower activity and olefin selectivity, in spite of higher Co dispersion, than Co/SiO2 catalysts. The catalytic performance depends on the amount of reducible Co species, which again depends upon the optimum content of Ru.