Oxidative desulfurization of model fuels with pure nano-TiO2 as catalyst directly without UV irradiation

In this study, different crystalline forms of nano-TiO2 were prepared using the sol–gel method. The TiO2 particles were characterized by X-ray diffraction, transmission electron microscopy, and nitrogen adsorption/desorption measurements. The prepared nano-TiO2 was directly used as a catalyst to remove dibenzothiophene (DBT) from an octane solution without UV irradiation and with H2O2 aqueous solution as an oxidant. Results showed that anatase TiO2 nanoparticles have excellent catalytic oxidative activity because conversions as high as 100% were obtained within 50 s under the experimental conditions; by contrast, conversion rates obtained from anatase–rutile and amorphous nanoparticles reached only 48.1% and 25.7%, respectively. The effects of stirring rate, reaction temperature, initial DBT concentration, catalyst amount, and oxidant content were also investigated in detail. Based on the results, a reaction kinetic model implying a first-order reaction with an activation energy of 56 kJ/mol was established. The nano-TiO2 particles were used to catalyze 4,6-dimethyldibenzothiophene, and the effects of reaction temperature and amount of oxidant used on this reaction were investigated.