Fischer-Tropsch synthesis: evaluation of Gd and Ru promoters effect on Co/γ-Al2O3 catalyst at different conditions

In this study, the effect of Ru and Gd promoters on 15Co/-Al2O3 catalyst in the Fischer-Tropsch synthesis is investigated. The catalysts were synthesized by dry impregnation method and characterized by XRD, adsorption/desorption of nitrogen, TPR, TEM, ICP and XPS analyses. Activity and selectivity of the catalysts were examined in a fixed bed reactor at 210-230 A degrees C with a H-2/CO ratio of 2 and atmospheric pressure. The results showed that the Ru-promoted catalyst has the highest activity and methane selectivity which reduce the chain growth probability. The Gd-promoted catalyst was shown smaller particle size and higher dispersion of cobalt particles in compared with unpromoted catalyst. The smaller particles have more interaction and thus show the lower catalyst reducibility. The presence of Gd in the catalyst cause higher chain growth probability compared to the unpromoted one. The Ru-Gd-promoted catalysts were shown a synergic effect in the catalyst reducibility. Based on the screening of the catalysts in the atmospheric pressure; the unpromoted, 0.1Ru/15Co/Al2O3, and 0.1Ru1Gd/15Co/Al2O3 catalysts were selected to test at high pressure conditions, which the 0.1Ru1Gd/15Co catalyst showed the highest C-5 (+) selectivity (75%) compared with the 0.1Ru/15Co/Al2O3 and the unpromoted one.