EFFECTS OF TRANSITION-METAL ADDITION TO COMO/GAMMA-AL2O3 CATALYST ON THE HYDROTREATING REACTIONS OF ATMOSPHERIC RESIDUAL OIL

The effects of transition metal addition to a commercial CoMo/gamma-Al2O3 catalyst on the hydrotreatment of atmospheric residual oil were investigated using a continuous flow fixed bed reactor operated at 420-degrees-C and 6.9 MPa. Nickel, ruthenium and tungsten were used as an additive to the catalyst. Catalyst performances were evaluated in terms of activities and initial deactivation rates in sulfur removal, conversion of heavier to lighter oil fractions, and removal of asphaltenes. Among the metal additive-modified CoMo/gamma-Al2O3 catalysts, NiCoMo/gamma-Al2O3 and WCoMo/gamma-Al2O3 showed a more improved reaction performance than commercial CoMo/gamma-Al2O3 whereas RuCoMo/gamma-Al2O3 did not. The performance improvements observed after addition of nickel or tungsten were thought to be mainly a result of the promotion effect on the catalytic activity in hydrodesulfurization. Significant improvements of catalyst performance were obtained by the addition of a small amount of tungsten (0.5 wt.-%). Tungsten was considered to be promising as a secondary promoter of CoMo/gamma-Al2O3.