Evaluación de carburos de Mo, Co-Mo y Ni-Mo soportados sobre carbón activado para la hidrodesulfuración de tiofeno

Mo, Co-Mo, and Ni-Mo catalytic precursors (20 wt% active phase) supported on microporous activated carbon were synthesized by wet impregnation of ammonium heptamolybdate, nickel nitrate and cobalt sulfate solutions. The oxidic precursors were submitted to a carbiding treatment with a 20% CH ₄/H₂ gas mixture, heating at 5°C/min up to 700°C. The resulting solids were characterized by X-Ray Diffaction (XRD), Infrared spectroscopy (FT-IR) and surface area measurements (SSA) from nitrogen physisorption data. XRD results indicated that the Co-Mo/CA catalyst suffered the strongest structural changes. FT-IR showed the signals corresponding to the support and the supported species. SSA of the oxidic samples decreased respect to the support, but increased after the carbiding treatment for the Co-Mo/CA sample. Catalysts were presulfided in situ with CS₂/H₂ mixture and evaluated in thiophene hydrodesulfurization at normal pressure and 350°C, starting from both oxidic and carbided states. The observed thiophene conversions were similar for oxidic and carbided precursors, only the oxidic Ni-Mo/CA sample showed a higher conversion than the carbided sample.