A microwave-ultrasound assisted synthesis of defective TiO2 and WO3/TiO2 nanoparticles for ultralow sulfur diesel production

A novel synthesis of W5+0.247W6+0.753O2.886/TiO2 nanomaterials via the microwave-ultrasound assisted method was reported. TiO2 nanoparticles with crystallite size around 6 nm was obtained with only 5 min microwave and ultrasound irradiation. WO3/TiO2 catalyst contained 442 mu mol/g Lewis acid sites and 3.82 % oxygen defects in the WO3 crystals. For the ultralow sulfur fuel production, the WO3/TiO2 catalyst could rapidly oxidize 97 % of 4,6-dimethyldibenzothiophene (4,6-DMDBT) in 20 min using H2O2 as oxidant and formic acid as promoter in a model diesel. Formation of oxygen defects, peroxometallic species, and Lewis acid sites in catalyst surface played the key roles in the 4,6-DMDBT oxidation.