Photocatalytic oxidative desulfurization of dibenzothiophene under simulated sunlight irradiation with mixed-phase Fe2O3 prepared by solution combustion

Mixed-phase Fe2O3 was prepared from Fe(NO3)(3) and (C2H5)(3)NHCl via solution combustion. Photocatalytic oxidative desulfurization of dibenzothiophene (DBT) under simulated sunlight irradiation using mixed-phases of alpha- and beta-Fe2O3 as catalysts was investigated. The DBT in the oil phase was extracted into water phase and then photooxidized to CO2 and SO42- by Fe2O3 and O-2 dissolved in water. The Fe2O3 containing 36.6% beta-Fe2O3 and 63.4% alpha-Fe2O3 exhibited the highest photocatalytic activity. Sulfur removal of DBT in n-octane was 92.3% for 90 min irradiation under the conditions of V(water):V(n-octane) = 1 : 1, air flow rate at 150 mL min(-1), and Fe2O3 addition at 0.05 g. The kinetics of photooxidative desulfurization of DBT was a pseudo-first-order with an apparent rate constant of 0.0287 min(-1) and half-time of 24.15 min. The sulfur content of the actual diesel could be reduced from 478 mu g mL(-1) to 44.5 mu g mL(-1) after 90 min. The radical scavengers experiments and terephthalic acid fluorescence technique indicated that (OH)-O-center dot and O-2(center dot-) were the main reactive species in the DBT photocatalytic degradation. A potential photocatalytic desulfurization mechanism using mixed-phase Fe2O3 was proposed.