Influence of high Mo loading on the HYD/HDS selectivity of alumina supported MoS2 catalysts

High loading Mo/alumina catalysts have been tested for the simultaneous hydrodesulphurisation of dibenzothiophene and hydrogenation of 1-methyl naphthalene in presence of isoquinoline at 3MPa, 623 K. In these conditions, it is found that the HYD/HDS activity ratio is increasing when the Mo loading increases. All used catalysts have been found well sulphided as indicated by X-ray photoelectron spectroscopy. Transmission electron microscopy analysis indicated that the detected MoS2 slabs have a mean length varying from 25 to 40 Angstrom and a number of slab per stack increasing from 1.1 to 1.4 when the Mo loading increases. Assuming that the detected slabs are representative of the active phase morphology, only the HYD activity is found to correlate well with the number of edge or edge+corner surface sites in the range of Mo loading investigated.