Effect of Fe doped over V–Sb oxide catalyst in toluene selective oxidation

Mixed oxides FexV1−x SbO4 with x = 0–1.0 were prepared by slurry method and characterized by X-ray diffraction (XRD), Mössbauer spectroscopy, and temperature-programmed reduction (TPR). The samples with x = 0, 0.4 and 1.0 were evaluated as catalyst in vapor phase toluene partial oxidation reaction. It was found by XRD that Fe, as doping, was introduced in the rutile structure of VSbO4. The BET surface area of partially substituted solid with x = 0.4 was higher than those obtained for VSbO4 and FeSbO4 samples. It was shown that V is responsible of the hydrocarbon molecule activation. The catalyst with Fe x = 0.4 presented lower specific rate reaction and lower selectivity to total oxidation products than undoped solid (VSbO4), which it would be related to a partial replace of V by Fe in the V–O–V chains. In conclusion, the solid activity and selectivity to total oxidation decrease due to a higher isolation of V sites, when V3+ is substituted by Fe3+ in the rutile structure.