Platinum Doped Hydrotreating Catalysts for Deep Hydrodesulfurization of Diesel Fuels
Résumé
Two-stage processes are possible solutions for reaching 10 ppm sulfur in gas oil without severe running conditions. First, most of the sulfur is removed by using a CoMo conventional catalyst. Second, after H2S removal, the treated oil, with a remaining S content below 500 ppm, is again hydrotreated. In this latter case, the use of noble metal catalysts can be envisaged. In the present study dealing with this second stage reactor, we examined a catalytic system based on the addition of a low content of Pt to a commercial sulfide catalyst. An enhancement in catalytic activity can be obtained in the conversion of model molecules (tetralin and dibenzothiophene) as well as a hydrotreated straight run gas oil. The promotion effect strongly depends on the preparation procedure which requires the impregnation of Pt on a presulfided commercial HDT catalyst. Advanced EXAFS and HRTEM characterizations were used to characterize the active phases.