Influence of sub-stoichiometric sorbitol addition modes on the structure and catalytic performance of alumina-supported cobalt Fischer–Tropsch catalysts

This paper focuses on the influence of different modes of sub-stoichiometric addition of sorbitol during catalyst preparation on the structure and performance of alumina-supported cobalt catalysts in Fischer–Tropsch synthesis. The catalysts are prepared using either alumina support pretreated with sorbitol or using co-impregnation of alumina support or using co-impregnation of calcined cobalt catalyst or catalyst post-treatment with sorbitol. It is found that the catalyst structure and catalytic performance are strongly affected by sorbitol addition mode. The catalysts prepared using support pretreatment with sorbitol or sorbitol addition during first impregnation step display an enhanced cobalt dispersion which is accompanied by a spectacular increase in Fischer–Tropsch reaction rate and hydrocarbon productivity.

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► The catalyst structure and performance of alumina-supported cobalt Fischer–Tropsch catalysts are strongly affected by sorbitol addition mode.
► Alumina pretreatment with sorbitol and sorbitol addition during first impregnation step dramatically enhance cobalt dispersion and result in a spectacular increase in Fischer–Tropsch reaction rate.
► The observed phenomena can be interpreted by different mechanisms of decomposition of cobalt precursor and crystallization of Co3O4 phase in the presence of sorbitol.