Reactions of alpha-olefins of different chain length added during Fischer-Tropsch synthesis on a cobalt catalyst in a slurry reactor

Based on the picture of Fischer-Tropsch synthesis as an ideal polymerizatio n reaction it is easily noticeable that primarily formed product olefins ca n undergo secondary reactions, which generally lead to carbon number depend encies of certain olefin reaction pathways and thereby to modifications of product distributions. To obtain more insight into the role of secondary ol efin reactions during Fischer-Tropsch synthesis and the reason for their ch ain length dependence, extensive studies on their extent and selectivity an d particularly their chain length dependence at different reaction conditio ns (variation of CO partial pressure and reaction temperature) were perform ed by co-feeding alpha-olefins (C-2-C-11) during FT synthesis with cobalt c atalysts in a gradientless slurry reactor. Conversion of the added olefins revealed a strong carbon number dependence exhibiting a sharp minimum at C- 3. The observed chain length dependencies of individual reaction pathways ( hydrogenation and incorporation) are in agreement with the selectivities ob served in the base case experiments without olefin addition and mainly due to carbon number dependent solubility of the olefins in the liquid reaction product. (C)1999 Elsevier Science B.V. All rights reserved.