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-Al 2O3 catalyst on the hydrotreatment of atmospheric residual oil were in vestigated using a continuous flow fixed bed reactor operated at 420-d egrees-C and 6.9 MPa. Nickel, ruthenium and tungsten were used as an a dditive to the catalyst. Catalyst performances were evaluated in terms of activities and initial deactivation rates in sulfur removal, conve rsion 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 perf ormance than commercial CoMo/gamma-Al2O3 whereas RuCoMo/gamma-Al2O3 di d 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 improv ements of catalyst performance were obtained by the addition of a smal l amount of tungsten (0.5 wt.-%). Tungsten was considered to be promis ing as a secondary promoter of CoMo/gamma-Al2O3.