Hierarchical porous HPW/titania-silica material with superior adsorption-catalytic oxidation activity for multi-ring thiophenic sulfur compounds
A series of hierarchically structured HPW/titania-silica catalysts with micro-meso-macroporous structure and high specific surface area are prepared through a co-precipitation method, adopting cationic surfactant STAB and monodisperse PS microspheres as double templates. The effects of silicon content on the specific surface area, mesoporous ordering, crystalline phase, and surface acidity of Ti-Si composites have been investigated by SEM, TEM, XRD, BET, XPS, NH3-TPD, UV-Vis/DRS, and FT-IR measurements. These results suggest that as-fabricated catalyst with 80% SiO2 content possesses a relatively high SBET (1001.1 m2/g), crystal characteristics of anatase TiO2, and weak Lewis acid site on the material surface. Keggin-type of H3P12W40 is homogeneously dispersed in SiO2-TiO2 framework. In the oxidative desulfurization (ODS) reaction, 500 ppm of dibenzothiophene (DBT) in the model fuel can be completely removed within 60 min under the condition of catalyst dosage = 0.05 g T = 30 oC, O/S = 4. The excellent ODS performance is due to the advantages of interconnected macropores, short-range-ordered mesopores, abundant micropores, and surface acidity of catalyst, which facilitates the mass transfer of DBT adsorption and diffusion process in pore channel. The hierarchical micro-meso-macroporous structure of catalyst also benefits for the exposure of inner surface area, increases the amount of accessible active sites and the exposure of inner surface. Moreover, as-fabricated catalyst can be reused for 10 cycles without signiﬁcant decrease in desulfurization efficiency.