Page 271 - Lignocellulosic Biomass to Liquid Biofuels

Fischer Tropsch synthesis of syngas to liquid hydrocarbons 227

Table 7.3 Role of different promoters on catalytic behaviors of Co-based
Fischer Tropsch (FT) catalysts.
Promoters Prospective effect References

Earth oxides The appropriate amount of CeO 2 increases [41,87 90]
(CeO 2 and the active sites of the catalysts due to the
La 2 O 3 ) increase of reducibility and dispersion,
which increases the FT synthesis activity.
Inhibit H 2 O reoxidation as well as further the
aggregation of cobalt metal particles during
the reaction. Also, the CO conversion
increased with a proper amount and
preparation method.
The selectivity of C 51 hydrocarbons is
increased. Also, the ratio of olefin/paraffin
ratio increased after modifying the Co
support interactions with La 2 O 3 .
Noble metals (Pt, The Pt resulted in a significant increase in the [53,91 94]
Pd, Re, and FT reaction rate but decrease the selectivity
Ru) of C 51 hydrocarbon. Also, Pt and Pd
showed higher CH 4 selectivity and hardly
exerted any effect on the degree of cobalt
reduction.
Pt and Pd increased the degree of cobalt
reduction but decreased the TOF.
Re enhanced the activity for FT synthesis,
which increases the selectivity of C 51 and
decreases CH 4 selectivity. Also, Re raised
the dispersion of Co catalysts.
Ru increased the catalytic activity and TOF,
but the CH 4 selectivity was unchanged.
ZrO 2 Increases the Co metal active sites and [87,95,96]
reducibility, leading to the increase of CO
conversion and C 51 selectivity. The
increasing content of Zr decreased the CH 4
selectivity. Also it decreases the ratio of
olefin to paraffin in the products.
Increasing the selectivity of C 51 due to the
increased Co site density and the lowered
hydrogenation activity.
Mn Increases the selectivity to C 51 and decreases [97 99]
CH 4 production due to decreasing the
hydrogenation reaction, which increases the
ratio of olefin to paraffin.
Possibly decreases the CO conversion activity
if the Mn content is high.
TOF, Turnover frequency.