Investigation of bifunctional zeolite supported cobalt Fischer-Tropsch catalysts Original Research Article

ZSM-5, ZSM-11, ZSM-12 and ZSM-34 were examined as supports for cobalt bifunctional Fischer-Tropsch catalysts in order to determine the influence of zeolite pore structure on the synthesis. All supports produced reasonably active catalysts, with activity increasing with the channel size of the zeolite support (i.e. in the order of ZSM-34 ZSM-5 > ZSM-11 > ZSM-12. Contrary to initial expectations, the hydrocarbon products became lighter, and contained less n-alkanes as the acidity of the zeolite was reduced (which was in the same order as when the channel size of the zeolite was increased). This indicated that for this strongly acidic series of zeolites, accessibility to internal acid sites was more important in influencing the degree of secondary acid catalysed restructuring reactions of the primary Fischer-Tropsch products than was the strength or concentration of these acid sites.