Al-SBA-15 as a support of catalysts based on chromium sulfide for sulfur removal

SBA-15 doped with aluminium supported Cr catalysts were prepared with different chromium contents by the wetness impregnation method. The materials in oxidic and sulfided states were characterized by X-ray diffraction (XRD), N2 adsorption–desorption isotherms at 77K, NH3-TPD, XPS analysis and H2-TPRS. The catalytic properties of these materials with the hydrodesulfurization (HDS) of dibenzothiophene (DBT) were tested at 260–340 °C under a hydrogen pressure of 3.0 MPa. The catalytic behaviour was studied as a function of the Cr loading and the support. A mesoporous silica (SBA-15) was also used to prepare the Cr catalysts in order to study the influence of the support on the catalytic performance. The catalyst based on SBA-15 showed very low catalytic activity in the reaction conditions studied whereas the AlSBA-15 based catalyst showed very good performance in hydrotreating, depending on the Cr loading. These results suggest that catalytic activity, which is directly related to the amount of labile sulfur, can vary not only as a function of the Cr content, but also with the incorporation of aluminium to the mesoporous silica. This highly modifies the nature of the acidic properties of the support, providing a stronger metal–support interaction, allowing better dispersion of the chromium species and specific electronic properties of the active species that affect the catalyst performance.