Effect of Cobalt Source on the Catalyst Reducibility and Activity of Boron-modified Co / TiO₂ Fischer-Tropsch Catalysts

Abstract

The effect of cobalt precursor (nitrate, acetate and chloride salts) on the catalyst reducibility and dispersion, as well as the catalytic activity of the Fischer-Tropsch (FT) synthesis, of boron-modified titania-supported cobalt catalysts (0.1%B/10%Co/TiO2) has been investigated. FT studies were performed on both calcined and uncalcined catalysts prepared from the three cobalt sources. The uncalcined nitrate catalyst showed a higher activity for FT synthesis compared to the uncalcined acetate and chloride catalysts. For the calcined catalysts, the acetate and nitrate catalysts exhibited higher FT activity. The low activity associated with the chloride catalyst related to poisoning by residual chloride ions. Calcination was found to enhance the extent of cobalt bulk reduction and FT activity for all three of the catalysts. The FT reaction rate increased with increasing percentage cobalt dispersion while the turnover frequency (TOF) was found be near independent of cobalt source.


South African Journal of Chemistry Vol.56 2003: 1-4