Fischer-Tropsch synthesis : influence of support on the impact of co-fed water for cobalt-based catalysts

Co catalysts were prepared with variable cobalt oxide-support interactions through judicious selection of the cobalt loading, the type of support utilized, and the promoter employed, if any, along with its loading. For a comparable Co loading range, while a positive effect of water was found for catalysts identified to have supports that only weakly interacted with the cobalt clusters, an adverse impact of water was recorded when cobalt was supported on more strongly interacting supports, such as TiO 2 and especially, Al 2 O 3 . However, alumina supported cobalt catalysts were found to have much higher active site densities in the cobalt loading range explored, due to a smaller average crystallite size. More robust Co/Al 2 O 3 catalysts, less sensitive to the negative effect of water, were obtained at higher Co loadings, where the average cluster size was > 10 nm.