HDS of 4,6-DMDBT over NiMoP/(x)Ti-SBA-15 catalysts prepared with H3PMo12O40
Résumé
HDS of 4,6-DMDBT over NiMoP/SBA-15 and NiMoP/(x)TiSBA-15 catalysts prepared using an heteropolyacid (H3PMo12O40) and nickel citrate (C12H10N13O14) 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 similar to 100 K. The results show that for catalysts supported on pure SBA-15 the noncalcined catalyst prepared with H3PMo12O40 (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 TiO2 was incorporated to SBA-15 and the catalyst was calcined at 773 K. This catalyst presented the highest TOF.