MAGNESIA SUPPORTED NI-MO SULFIDE HYDRODESULFURIZATION AND HYDRODENITROGENATION CATALYSTS PREPARED BY NONAQUEOUS IMPREGNATION

Magnesia supported Ni-Mo sulfide catalysts were prepared by three meth ods: by impregnation from aqueous solutions, by precipitation-adsorpti on of sulfides in a water-toluene emulsion, and by impregnation from n on-aqueous solutions using dimethylsulfoxide and methanol as solvents. They were tested in: (i) the single hydrodesulfurization of thiophene (HDS), and (ii) the parallel hydrodesulfurization of thiophene (HDS,P Y) and the hydrodenitrogenation of pyridine (HDN). The reference Ni-Mo /alumina catalyst was the commercial sample Shell 324. The catalytic a ctivity of samples prepared by aqueous impregnation and by precipitati on-adsorption was low, activity for (HDS) and (HDN) of the best sample being only about 30 and 20%, respectively, of the activity of the She ll 324 catalyst at 320 degrees C. The chemical and textural instabilit y of the high surface area magnesia in aqueous solutions was the limit ing factor. Much higher activity was achieved by non-aqueous impregnat ion, activity of the best Ni-Mo/MgO sample prepared by this method for (HDS), (HDS,PY) and (HDN) being 94, 290 and 105%, respectively, of th e activity of the Shell 324 catalyst at 320 degrees C. As compared wit h the alumina supported catalyst, the special feature of the Ni-Mo/MgO catalysts irrespective of the preparation method was lower inhibition of HDS by parallel HDN and lower selectivity to HDN in parallel HDN a nd HDS.