Characterization and HDS activity of sulfided Co[sbnd]Mo[sbnd]W/SBA-16 catalysts: Effects of P addition and Mo/(Mo + W) ratio.

Two series of SBA-16-supported Co Mo W ternary sulfide catalysts with atomic ratio r = Mo/(Mo + W) ranging from 0.3 to 0.7 were prepared by the simultaneous impregnation of SBA-16 and phosphated-SBA-16 substrates with metal precursors. The samples were characterized by a variety of techniques (chemical analysis, N 2 physisorption, SEM, XRD, DRS UV–vis, TPR, TPD-NH 3 , Raman spectroscopy, HRTEM, XPS and coke burning) . The catalytic performance was evaluated in the hydrodesulphurization (HDS) of dibenzothiophene (DBT), carried out in a batch reactor at 350 °C and 3.1 MPa of total H 2 pressure. The maximum activity at the same atomic ratio r = 0.4 was observed for the catalysts supported on SBA-16 modified with phosphorous ( r = 0.4(P)). HRTEM evidenced that this was because different MoS 2 crystalline structures were formed: the P-free sample prepared with Mo/(Mo + W) atomic ratio of 0.6 ( r = 0.6) exhibited the MoS 2 -2H crystalline structure whereas the P-containing samples prepared with Mo/(Mo + W) atomic ratio of 0.4 ( r = 0.4(P)) exhibited the interplanar distance corresponding to (0 0 3) planes of MoS 2 -3R crystalline structure. Additionally, the best activity of the r = 0.4(P) sulfide catalyst was linked with the enhancement of the WS 2 species surface exposure accompanied with a larger sulfidation degree of W species (from XPS). [ABSTRACT FROM AUTHOR]