HDS of 4,6-DMDBT over NiMoP/(x)Ti-SBA-15 catalysts prepared with H ₃PMo ₁₂O ₄₀

HDS of 4,6-DMDBT over NiMoP/SBA-15 and NiMoP/(x)TiSBA-15 catalysts prepared using an heteropolyacid (H ₃PMo ₁₂O ₄₀) and nickel citrate (C ₁₂H ₁₀Ni ₃O ₁₄) as Mo and Ni precursors was studied. To analyze the effect of calcination temperature on HDS activity, catalysts noncalcined and calcined at 773 K were prepared. The performance of the different catalysts during the hydrodesulfurization of 4,6-dimethyldibenzothiophene was compared with that of a reference catalyst prepared by impregnation with a solution containing ammonium heptamolybdate and nickel nitrate. Kinetic parameters for the HDS of 4,6-DMDBT were estimated using a simplified kinetic model. The catalysts were characterized by N ₂ physisorption, X-ray diffraction, Raman, and IR of adsorbed CO at ∼100 K. The results show that for catalysts supported on pure SBA-15 the noncalcined catalyst prepared with H ₃PMo ₁₂O ₄₀ (NiMoP(H-nc)/SBA-15) presents the highest number of active sites, the higher apparent reaction rate constant for the hydrogenation route, and therefore the best 4,6-DMDBT HDS activity. In contrast, for Ti-modified catalysts, NiMoP/(x)Ti-SBA-15, the highest HDS activity was found when 15% of TiO ₂ was incorporated to SBA-15 and the catalyst was calcined at 773 K. This catalyst presented the highest TOF.