Comparative study of WS2 and CodNi/WS2 HDS catalysts prepared by ex situ/in situ activation of ammonium thiotungstate

A comparative study of the syntheses of unsupported WS2 and M/WS2 (M = Co, Ni) catalysts by ex situ/in situ decomposition of ammonium thiotungstate (ATT) is herein reported. Ex situ activation was performed under a H2S (15% volume)/H-2 flow, whereas in situ activation consists in the direct decomposition of ATT or Co(Ni)/ATT precursors in the presence of a hydrocarbon solvent during the hydrodesulfurization (HDS) of dibenzothiophene (DBT). Precursors were characterized by thermogravimetric analysis and final catalysts by X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area (BET). Catalysts activated using the in situ mode of activation present higher specific surface areas with the noticeable exception of the Ni/ATT precursor. Activity measurements showed that the in situ activated WS2 and Ni/WS2 catalysts exhibit higher activity than the ex situ activated catalysts.