Preparation, characterization and catalytic properties of unsupported vanadium sulphides

This work concerns the preparation and the ability of unsupported vanadium sulphide to catalyze different reactions representative of hydrotreatment. Pure V₂S₃ was prepared by decomposition of ammonium thiovanadate at relatively low temperature. The reactivity of the decomposed solid towards oxygen confirms the high oxophilic character of this group V sulphide. The oxidation mechanism involves a superficial oxidation followed by an insertion of oxygen into the lacunar structure of the solid. The comparison of the catalytic properties of this chalcogenide with those of molybdenum or tungsten sulphides shows the superiority of vanadium sulphide for performing hydrogenation reaction of various cyclic molecules. In contrast, the hydrodesulphurization properties are of the same order.