Promotion of cobalt catalysts for the Fischer-Tropsch synthesis with alkali metals

Abstract

The promotion of supported cobalt catalysts for the synthesis of hydrocarbons from CO and H2 with alkali metals was studied. The catalysts were characterized by X-ray diffraction analysis, oxygen titration, and the temperature-programmed desorption (TPD) of CO. Catalytic tests showed that the introduction of alkaline promoters increases selectivity for higher hydrocarbons, decreases selectivity for methane, and also increases the concentration of olefins in the gasoline fraction of products. The promoting effect depends on the catalyst preparation method. The TPD of CO was used to demonstrate that the greatest amount of CO was adsorbed on the surface of a catalyst promoted with potassium; in this case, the strength of CO binding on this catalyst reached a maximum. The data of the TPD of CO correspond to the highest selectivity of a cobalt-potassium catalyst for the formation of higher hydrocarbons.