Effects of Ruthenium on the Catalytic Performance of Cobalt-Based Hybrid Catalysts for Synthesis of Hydrocarbons from CO and H2

The study investigated a number of cobalt-based hybrid catalysts (prepared as composite mixtures) for integrated Fischer-Tropsch (FT) synthesis and hydroprocessing. The metal component was a Co-based catalyst for FT synthesis prepared by impregnation (Co-Al/SiO2 in one sample and Co-Ru/SiO2 in another); the acid component was a ZSM-5 zeolite in the H-form that additionally contained Ru (incorporated by impregnation in one sample and by ion exchange in another); and the binder was boehmite. The catalysts were characterized by XRD, low-temperature argon adsorption/desorption, EDX, SEM, TEM, H-2-TPD, and TPR. The promoter incorporation method was shown to affect the particle size and cobalt reduction conditions. The catalysts were tested in FT synthesis at 2.0 MPa, 240 degrees C, H-2/CO = 2, and GHSV 1000 h(-1). The method for loading Ru as a hydrogenating agent was found to govern the catalytic activity as well as the group and fractional compositions of the reaction products. It was further shown that co-loading Co and Ru intensifies the hydrogenation and synthesis of hydro-carbons-including C-11-C-18 (diesel fuel) and in particular iso-alkanes-and minimizes the content of unsaturated hydrocarbons. Incorporating Ru into the acid component favors the isomerization activity of the catalyst. Using impregnation for this purpose maximizes the gasoline productivity (C-5-C-10 hydrocarbons).