Phosphorus effect on Co//Mo and Ni//Mo synergism in hydrodesulphurization catalysts

The influence of P concentration on the synergism between Co/γ-Al2O3 or Ni/γ-Al2O3 and Mo/γ-Al2O3 stacked beds separated by a 3-mm stack of Px/γ-Al2O3 is studied in the hydrodesulphurization of gasoil under operating conditions similar to those of industry. The results shown increased Co//Mo and Ni//Mo synergism related to changes in zero point of charge (ZPC), acid strength, and band intensities of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy due to the incorporation of P into the γ-Al2O3 used as separator.

In the conventional hydrodesulphurization (HDS) catalysts type Co(or Ni)Mo/γ-Al2O3, including commercial catalysts, the effect of phosphorus on HDS activity can be well explained by an increase of synergism (Fso) Co//Mo and Ni//Mo caused by the increased mobility of spillover hydrogen on the OH phosphorus surface structure separating the crystallites CoSx or NiSx and MoS2 sulphides.Figure optionsDownload as PowerPoint slide