Unsupported Fe-V mixed sulfides: Characterization and VOOEP hydrodeporphyrinization

Bulk Fe-V mixed sulfide catalysts prepared by the co-precipitation method were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fe57 Mössbauer spectroscopy. Hydrodeporphyrinization (HDP) of vanadyl octaetil porphyrine (VOOEP) was used as a catalytic test. XRD and Mössbauer analysis showed the existence of two structural phases based on NiAs sub-cell, i.e. monoclinic (Fe, V)3S4 and hexagonal (Fe, V)1−xS. TEM micrographs reveal similar morphology (particle size and shape) for all the catalysts except for pure iron sulfide, which presented larger particle size. Mössbauer spectra of fresh and used catalysts indicate that phases are rather stable at reaction conditions. A correlation between specific HDP activity and the amount of monoclinic (Fe, V)3S4 phase is evidenced.