Carburos de Cobalto-Molibdeno soportados sobre carbón activado: Efecto del método de síntesis, velocidad de calentamiento, tipo de precursor de cobalto y agente presulfurante en la hidrodesulfuración de tiofeno

This work studied the Effect of the presulfiding agent, type of precursor (sulfate vs. nitrate of promotor), synthesis method (conventional vs. carbothermal carbiding) and heating rate in the hydrodesulfurization of thiophene over activated carbon supported cobalt-molybdenum carbides. The synthesis was carried out using the methods conventional (CH₄/H₂ (1:4)) and carbothermal with H₂ at 973 K and 1 or 5 K/min. The carbided phases were characterized by surface area (B.E.T), X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The surface areas were within a rank of 266 and 493m²/g, whereas the XRD analysis verified the presence of Co₆Mo₆C₂ for carbides obtained by carbothermal method independently of these variables. The XPS showed the presence on the surface of: Mo^{delta +}, Mo⁴⁺ and Mo⁶⁺, and Co²⁺ whose abundance was influenced by the synthesis method and type of precursor. On the order hand, XPS revealed that the carbides obtained by sulfate precursor retained sulfur on the surface as S^2- and SO₄^2-. Tests of thiophene HDS showed that carbides obtained by the carbothermal method had higher activity than those obtained by the conventional method when it was activated with CS₂/H₂ and inversely when used H₂S/H₂.