Highly active sulfided CoMo catalyst on nano-structured TiO2 |
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Authors: | J Escobar JA Toledo MA Cort s ML Mosqueira V P rez G Ferrat E L pez-Salinas and E Torres-Garcí a |
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Affiliation: | Prog. de Ing. Molecular y Materiales, Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas 152, San Bartolo Atepehuacan, Gustavo A. Madero, 07730, México DF, Mexico |
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Abstract: | High surface area (>300 m2 g?1) nano-structured TiO2 oxides (ns-T) were used as CoMo hydrodesulfurization catalyst support. Cylindrical extrudates were impregnated by incipient wetness with Mo (2.8 Mo at. nm?2) and Co (atomic ratio Co/(Co + Mo) = 0.3). Characterization of impregnated precursors was carried out by N2 physisorption, XRD and atomic absorption and laser-Raman spectroscopies. Sulfided catalysts (400 °C, H2S/H2) were studied by X-ray photoelectronic spectroscopy. As indicated by XRD and after various preparation steps (extrusion, Mo and Co impregnation and sulfiding) the nano-structured material was well preserved. XPS analyses showed that Co and Mo dispersion over the ns-T support was much higher than that on alumina. Very high surface S concentration suggested that even ns-T was partially sulfided during catalyst activation. Dibenzothiophene hydrodesulfurization activity (5.73 MPa, 320 °C, n-hexadecane as solvent) of CoMo/ns-T was two-fold to that of an alumina-supported commercial CoMo catalyst. The improvement was even more remarkable in intrinsic pseudo kinetic constant basis. No important differences in selectivity over the catalysts supported on either Al2O3 or ns-T were observed, where direct desulfurization to biphenyl was favored. Both Mo dispersion and sulfidability were enhanced on the ns-T support where Mo4+ fraction was notably increased (100%) as to that found on CoMo/Al2O3. |
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Keywords: | Sulfided CoMo Nano-structured TiO2 Dibenzothiophene hydrodesulfurization |
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