Synthesis and characterization of mesoporous phosphotungstic acid/TiO2 nanocomposite as a novel oxidative desulfurization catalyst

A series of mesoporous phosphotungstic acid/TiO2 (HPW/TiO2) nanocomposites with various HPW contents have been synthesized by evaporation-induced self-assembly method. These nanocomposites were used as catalysts for oxidative desulfurization of model fuel, which was composed of dibenzothiophene (DBT) and hydrocarbon, and used H2O2 as oxidant. These catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption isotherm, transmission electron microscopy (TEM), FTIR and UV–vis. Characterization results suggest that these mesoporous HPW/TiO2 possessed relatively uniform channel-like pores with Barrett–Joyner–Halenda (BJH) pore size of about 4 nm. The Brunauer–Emmett–Teller (BET) surface of the mesoporous HPW/TiO2 slightly increases with the increase of HPW content and reach to a peak value of 176 m2/g and 0.25 cm3/g when the HPW content is 30 wt%. Keggin-type heteropolyacids (HPAs) has been encapsulated into anatase TiO2 framework and the average size of TiO2 nanoparticles is 8 nm. Catalytic oxidation results show that the catalysts are very active in refractory bulky molecule organosulfur compounds in fuel oil. The oxidative removal of DBT increases as the HPW content increases. The mesoporous HPW/TiO2 also shows high selectivity for DBT oxidation in the DBT–petroleum ether–benzene system. The selective desulfurization ratio reach to 95.2% with mesoporous HPW/TiO2 (20 wt%) catalyst under the reaction condition of 333 K, 2 h. In addition, the mesoporous HPW/TiO2 catalyst shows excellent reusing ability, which makes it a promising catalyst in oxidative desulfurization process.

Graphical abstractMesoporous phosphotungstic acid/TiO2 (HPW/TiO2) nanocomposites, prepared by evaporation-induced self-assembly method, presents high catalytic active and selectivity in oxidative desulfurization of model fuel composed of dibenzothiophene (DBT) and hydrocarbon.Figure optionsDownload full-size imageDownload as PowerPoint slide