The Effect of Potassium on TiO2 Supported Bimetallic Cobalt-Iron Catalysts

The effect of potassium addition on Fischer-Tropsch catalysts containing 10 wt% cobalt and 2 wt% iron supported on pure TiO was studied using a continuous flow reactor at atmospheric pressure, a syngas feed with HCO = 1.7 and GHSV = 1944 mL g h. The FTS reaction was performed in a range of temperature 275-350 °C. Differences in textural, structural, chemical and redox properties of the materials were evaluated by N adsorption/desorption isotherms, XRD, XPS, and TPR. As compared to the catalyst without potassium, forming large quantity of methane at each of the three temperatures, the potassium promoted catalysts formed less methane and consistent amount of alcohols. Moreover, the potassium containing samples produced more of the heavier hydrocarbons and more CO at the higher temperature as compared to the potassium free sample. According to the structural-activity relationship potassium acted as both, structural and electronic modifier.