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, H2-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°C, H2/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 hydrocarbons—including C11–C18 (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 (C5–C10 hydrocarbons).