Electron-Paramagnetic-Resonance And Mossbauer Studies Of Fe3+ Ions In The Fe2o3-Moo3 System

The electron paramagnetic resonance (EPR) and Mossbauer spectra of iron-molybdenum mixed oxides system have been investigated. Both EPR and Mossbauer measurements revealed the formation of ferric molybdate, Fe2(MoO4)3 and the existence of two different Fe3+ species. The EPR spectra of Fe2(MoO4)3, show two resonance lines of Fe3+ ions indicating that a strong exchange interaction is dominates in pure iron molybdate. Mosbauer measurements revealed that the isomer shift (I.S) increases with increasing the iron content. A maximum of quadrupole splitting (Q.S) is observed at the stoichiometric concentration corresponding to the formation of Fe2(MoO4)3. The effect of a catalytaic dehydration process on the redox behaviour of Fe3+ located in iron molybdate frame work is investigated. Results indicate that the catalytaic dehydration of 2-proppanol over this catalyst reduces Fe3+ ions to Fe2+ leading to the formation of the inactive phase FeMoO4. the essential role of oxygen, in the alcohol gas feed, in regeneration the activity of the catalysts was demonstrated.