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

Abstract

Mixed oxides FexV1x SbO4 with x = 0–1.0 were prepared by slurry method and characterized by X-ray diffraction (XRD), Mo¨ssbauerspectroscopy, and temperature-programmed reduction (TPR). The samples with x = 0, 0.4 and 1.0 were evaluated as catalyst in vapor phase toluenepartial oxidation reaction. It was found by XRD that Fe, as doping, was introduced in the rutile structure of VSbO4. The BET surface area ofpartially substituted solid with x = 0.4 was higher than those obtained for VSbO4 and FeSbO4 samples. It was shown that V is responsible of thehydrocarbon molecule activation. The catalyst with Fe x = 0.4 presented lower specific rate reaction and lower selectivity to total oxidationproducts 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+ inthe rutile structure.