Evaluation of Ru-promoted Co/γ-Al2O3 catalysts in Fischer-Tropsch synthesis in a CSTR

Ruthenium-promoted cobalt/alumina catalysts were prepared by co-impregnation method and were evaluated in a continuously stirred-tank reactor. The catalysts were characterized by XRD, TGA, TPR, H2-chemisorption and BET surface area techniques. The loading of Co were 15 and 25 wt%, in different catalysts while the loading of Ru was 1 wt%. Characterization studies showed that Ru-promoted catalyst with lower cobalt content shows higher reducibility than that with higher cobalt content. The former also exhibits better cobalt dispersion, smaller particle size of the metal, and a larger pore volume. Fractional factorial experimental design was applied to catalysts for Fischer-Tropsch synthesis (FTS) to evaluate the influence of different parameters on catalytic performance. The reactor temperature, pressure, space velocity, mixer speed and Co loading were considered as the independent variables. Using this methodology, the best process conditions were obtained. The experimental results demonstrated that an increase in temperature results in an increase in CO conversion and C1 selectivity but reduction in C5+ selectivity. On the other hand, increasing cobalt loading, mixing speed and space velocity shift the products towards heavier compounds. The effect of Co loading on aging behavior of the catalyst was also studied.