Research On Co-Mo-Ni-W/g-Al₂O₃ Catalyst For Diesel Fuel Ultra-deep Desulfurization

The preparation, characterization, evaluation and modification of W-Mo-Ni-Co/γ-Al₂O₃ catalyst for diesel fuel ultra-deep desulfurization were studied in this article. After being prepared with step impregnating method, the structure of the catalyst of W-Mo-Ni-Co/γ-Al₂O₃ was characterized by BET, XRD, TPD, TPR, IR and TEM.The effects of pore enlargement agent, calcination temperature and preparing condition of impregnation solution on properties of supports, and the effects of calcination temperature of catalyst after first impregnation and active components on properties of catalysts were all investigated. In addition, the HDS and HDN performance of catalysts were evaluated in a highpressure microreactor utilizing FCC diesel oil as materials.The results show that the supports prepared by adding pore enlargement agent have appro- priate pore size distribution, specific surface area and pore volume. When calcined at the tem- perature of 550℃, the catalysts have good pore size distribution, mechanical strength and spe -cific surface area. The impregnation solution prepared at low temperature has stability and s- olubility. Various active components can disperse uniformly on the support when the catalyst cal-cined in 450℃after the first impregnation. The catalytic performance evaluation results show that catalysts exhibit high diesel hydrofining catalytic activity and good commercial prospects.The effects of reaction temperature and space velocity,H₂/Oil ratio on the hydrogenation performances of A2 hydrogenation catalysts were studied on a high-pressure microreactor utilizing straight diesel oil and FCC diesel oil. The results indicate that the catalysts have good activity and the ratio of HDS and HDN can be 96.4% and 96% respectively, when reaction temperature being 360℃, hydogen pressure being 6.7MPa, space velocity being 1.5-2.0h^-1 and H2/Oil ratio being 500/1.Based on the above studies, the modification of W-Mo-Ni-Co/γ- Al₂O₃catalyst with Y-Zeolite was further studied. The effect of Y-Zeolite on the acidity, HDN and HDS activity of W-Mo-Ni-Co/γ- Al₂O₃ catalysts has been investigated, and the acidity of the catalysts was characterized as well. The results demonstrate that the hydrofining catalytic activity of catalysts was greatly improved when Y-Zeolite was added at the amount of 9% on the supports.