High surface area MoO 3/MgO: preparation by reaction of MoO 3 and MgO in methanol or ethanol slurry and activity in hydrodesulfurization of benzothiophene

Abstract

High surface area MoO 3/MgO (200–300 m 2 g −1) catalysts were prepared and tested in hydrodesulphurization of benzothiophene. The new slurry impregnation method was used that overcome the problem of chemical and textural instability of MgO support in aqueous impregnation solution of ammonium heptamolybdate. Molybdena was deposited by the reaction of MgO with the slurry of MoO 3 in aqueous methanol or ethanol at room temperature. Small amount of water added to alcohol (4 and 6% for methanol and ethanol, respectively) did not hurt texture of MgO and accelerated the impregnation reaction. The method is a special case of equilibrium adsorption impregnation. The maximum (saturated) amount of MoO 3 deposited on MgO of surface area of about 250 m 2 g −1 was about 22 wt.% MoO 3. However, hydrodesulphurization activity increased linearly only up to the loading of 15–20 wt.% MoO 3. XRD confirmed that molybdena is deposited in finely dispersed form. Hydrodesulphurization activity of the best MoO 3/MgO samples was the same as activity of the reference industrial MoO 3/Al 2O 3 catalyst.