CoMo/ZrO2 Hydrodesulfurization Catalysts Prepared by Chelating Agent Assisted Spreading

The Mo/ZrO2 and CoMo/ZrO2 catalysts were prepared by impregnation of the monoclinic ZrO2 by the chelating agent nitrilotriacetic acid (NTA) assisted spreading of MoO3 with CoCO3, or (NH4)6Mo7O24.4H2O with Co(NO3)2.6H2O. The catalysts were characterized by X-ray diffraction, N2 physisorption, O2 chemisorption and activity in reaction of 1-benzothiophene hydrodesulfurization. The properties of these unconventional catalysts were compared with behavior of conventional Mo/ZrO2 and CoMo/ZrO2 catalysts prepared by subsequent impregnation of the support with aqueous solution of (NH4)6Mo7O24.4H2O and Co(NO3)2.6H2O with calcination at 400 °C and with industrial Al2O3 supported samples. The application of NTA during the CoMo/ZrO2 catalysts preparation systematically increased the hydrodesulfurization activity by the factor 1.2-1.7. The optimal molar ratio NTA/(Co+Mo) to achieve high hydrodesulfurization activities was 1/1. The most active CoMo/ZrO2 catalyst was prepared by the impregnation with the solution made by dissolution of MoO3, CoCO3 and NTA in water followed by sulfidation without previous calcination.