3-STAGE DEEP HYDRODESULFURIZATION AND DECOLORIZATION OF DIESEL FUEL WITH COMO AND NIMO CATALYSTS AT RELATIVELY LOW-PRESSURE

Three-stage deep desulfurization of diesel fuel was performed using CoMo in the first stage and NiMo in the other two stages under H2 at 2.9 MPa. The first and second stages were carried out at higher temperature for sufficient desulfurization of benzothiophenes and dibenzothiophenes respectively, and the third stage was carried out at lower temperature to remove the fluorescent colour from the desulfurized oil. A sulfur content of <200 ppmw was achieved as well as decolorization. The influence of the reaction conditions in the different stages on hydrodesulfurization and fluorescent colour development and removal were examined in detail.