Mossbauer spectroscopy studies of iron catalysts from a Fischer-Tropsc
h (FT) Pilot Plant run at different time-on-stream periods were carrie
d out. Magnetite Fe3O4 was found to be active for the water-gas-shift
(WGS) reaction which accompanies the FT synthesis reaction over Fe-bas
ed catalysts. A correlation between the ratio of the occupancy of octa
hedral sites to the tetrahedral sites in magnetite to the WGS activity
was found. Cation-deficient magnetite gave higher WGS activity as com
pared to the stoichiometric phase.