Study of Co, Ru/SBA-15 type materials for Fischer-Tropsch synthesis in fixed bed tubular reactor: I. Effect of the high Ru content on the catalytic activity

A study was made on the influence of ruthenium as a promoter of supported Co/SBA-15 catalysts for the Fischer-Tropsch synthesis (FTS). The catalysts with 20% Co and Ru (0.1-5 wt%) were prepared by incipient wetness impregnation and were characterized by XRD, N₂ adsorption-desorption, TPR, AAS, oxygen consumption, SEM and TEM. A significant reduction of the specific surface area (SA) and an increase of the pore volume (V_p) were verified in the series of SBA-15 based materials, which can be attributed to a partial blockage of the pores, due to the presence of Co₃O₄ aggregates within the channels, together with the partial destruction of the pore arrays with the increasing Ru contents. The Cobalt dispersion and its reducibility degree were found relevant for explaining the catalytic activity and these parameters seem related with each other, as well as with the number of surface active sites (Co⁰). A high selectivity to C₅₊ hydrocarbons, together with a reduction of methane selectivity was obtained with a higher concentration of Ru, which can be attributed to a better reducibility of the metal phase.