Magneto-chemical character studies of iron-moly and iron-cobalt-moly catalysts

Iron, cobalt and molybdenum compounds are extensively used for the conversi on of coal to liquid fuels. To examine the correlations between catalytic, magnetic, and spectroscopic properties, we investigated the Zero-field Nucl ear Magnetic Resonance spectra of cobalt, Mossbauer spectra of iron, FTIR s pectra and magnetic character of the composite for a series of Fe/MoO3 and Fe/Co/MoO3 catalysts with different inter-metallic ratios and metal loading s. All the precursors are paramagnetic according to the magnetization data. Mossbauer results show that in the precursors Fe is in Fe3+ state. FTIR sp ectra reveal bands due to monodentate and bidentate structures of Fe-MoO3 a nd Co-MoO3. NMR spectra support these findings indicating strong inter-meta llic interaction between Co and MoO3. FTIR results show that exposure to CO or syngas (CO+H-2), leads to dissociation of metal-MoO3 structures and Mos sbauer data shows the presence of excess lattice charge with iron in the Fe 2+ state. Only a minute portion of the composite gets reduced to metallic s tate. Cobalt seems to form cobalt carbonyl structures, while carbide format ions seem to occur with iron. Lack of free metal sites seems to be the reas on for the poor conversion of CO observed in the catalytic runs.