THE EFFECT OF BORON ON HYD, HC AND HDS ACTIVITIES OF MODEL COMPOUNDS OVER NI-MO GAMMA-AL2O3-B2O3 CATALYSTS/

The effects of boron on the hydrogenation (HYD) of 1-methylnaphthalene (1-MNT), hydrocracking (HC) of diphenylmethane (DPM), and hydrodesulf urization (HDS) of dibenzothiophene (DBT) over sulfided Ni-Mo/gamma-Al 2O3-B2O3 catalysts have been studied. The results showed that the HC a ctivity of DPM slightly increases with the increase of B2O3; the HYD a ctivity of 1-MNT and the HDS activity of DBT first increase with incre asing amounts of B2O3, upto about 1 mol% of B2O3, and then decrease wi th increasing amounts of B2O3. The Ni-Mo/gamma-Al2O3-B2O3 catalysts ha ve been characterized by X-ray diffraction (XRD) and NH3 temperature-p rogrammed desorption (TPD). The addition of boron slightly improves th e acidity of the acid sites. However, when the loading of B2O3 in gamm a-Al2O3 reaches about 14 mol%, B2O3 phase first appears, and its conte nt increases with increasing load of B2O3. In Ni-Mo/gamma-Al2O3-B2O3 c atalysts, when the loading of B2O3 reaches 5 mol%, MoO3 phase first ap pears and its content increases with increasing load of B2O3, indicati ng the lowering dispersion of the catalysts. Thus, the catalytic hydro processing activities of these model compounds over the Ni-Mo/gamma-Al 2O3 catalysts may be related to the acidity and metal dispersion of th e catalysts. (C) 1998 Elsevier Science B.V.