Characterization and catalytic performances of hydrotreatment catalysts prepared with silicium heteropolymolybdates: comparison with phosphorus doped catalysts Original Research Article

The CoMo-based catalysts were prepared by impregnation of a γ-alumina with Si-based heteropolycompounds solutions. The impregnating solution, the dried and the calcined catalysts were characterized with various physical techniques. Based on these characterizations, a detailed description of the evolution of these entities during the preparation, as well as the nature of the surface oxomolybdate species of the oxidic precursor have been deduced. It is shown that the use of these Si-based heteropolycompounds allows increasing the thiophene conversion by comparison with classical preparation. This is assigned to the absence of foreign counter-ions in the impregnating solutions and to the formation of a different surface oxomolybdate phase. Moreover, comparison with phosphorus doped catalysts prepared with phosphorus heteropolycompounds suggests that the main role of phosphorus in the HDS catalysts consists in an optimization of the preparation of the oxidic precursor.