Preparation and Catalytic Evaluation of Cobalt-Based Monolithic and Powder Catalysts for Fischer−Tropsch Synthesis

Abstract

Cobalt-based monolithic and powder catalysts for Fischer−Tropsch synthesis were prepared. The alumina-supported catalysts contained cobalt (18.6 ± 0.9 wt %) and rhenium (1.2 ± 0.1 wt %) as active phases. To ensure the comparability of both catalysts, monolithic and powder catalysts were prepared from the same CoRe/γ-Al2O3 active powder. While the monolith was prepared by dip coating, the slurry for the coating procedure was also used for preparation of the powder catalyst. It could be shown that both catalysts have comparable composition, pore structure, Brunauer−Emmett−Teller (BET) surface area, and active metal surface area. Catalytic measurements with suspended powder catalyst in a stirred tank reactor and monolithic catalyst in a fixed-bed reactor in the slug-flow regime were performed during Fischer−Tropsch synthesis. Higher reaction rates at comparable methane selectivities were obtained with the monolithic catalyst. Estimations show that the advantageous mass-transfer characteristics of the monolithic catalyst in the slug-flow regime are responsible for this reaction rate enhancement.