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Photosensitized oxidative desulfurization of thiophene in n-octane/water extraction system with riboflavin as photosensitizer and O2 in air as oxidant was studied. A 500W high pressure Hg lamp was used as the light source for irradiation and air was introduced by a gas pump for supplying O2. The desulfurization yield of thiophene was 85.4% for a 5h photoirradiation under the conditions with the air flow at 150 ml•min-1, water/oil ratio at 1:1 and riboflavin concentration at 30µmol•L-1. The mechanism of photosensitized oxidative of thiophene is 1O2 exited from 3O2 by the addition of riboflavin. Under above conditions, the photooxidation kinetics of thiophene with O2/riboflavin is first-order with rate constant of 0.3277 h-1 and half-time of 1.37 h.

For the insolubility of binary phase system of oxidative desulfurization (ODS) , coordinated ionic liquid [3(C2H5)4NCl- (NH2)2CO] as efficient phase-transfer catalyst (PTC) have been applied to enhance the reaction. A coordinated ionic liquid which has been synthesized from urea and tetraethyl ammonium chloride is employed as efficient PTC for ODS of model oil in the present of hydrogen peroxide and acetic acid. The experimental results show that the desulfurization rate of thiophene is up to 70.68%, under the optimal conditions of O/S=3 (molar ratios), reactive time 30 min at 40degC. The optimal amount of coordinated ionic liquid PTC is 0.20 g / 18 mL model oil. The main products of oxidatiive thiophene by hydrogen peroxide and acetic acid are sulfone and sulfoxide of thiophene and SO/".

Photocatalytic oxidative kinetics of thiophene in n-octane/water extraction system was studied with nano-TiO2 powders as photocatalyst and O2 in air as oxidant. Influence of initial concentration of thiophene and addition of TiO2 on reaction rate constant and half time were investigated. Kinetics equation was founded. The results showed that the approviate addition of TiO2 was 0.1 g in 100 mL reaction system and the photooxidation kinetics of thiophene with TiO2 was first-order with rate constant of 0.6405 h-1 and half-time of 1.0822 h under the conditions with initial concentration of thiophene at 800 muLldrL-1 and addition of TiO2 at 0.1 g. The reaction rate constant increased with the decrease of initial concentration of thiophene.

Photochemical oxidation of thiophene in n-octane/acetonitrile extraction system using O2 as oxidant was studied. Results obtained here can be used as the reference for the oxidative desulfurization of gasoline because thiophene is one of the main components containing sulfur in fluid catalytic cracking gasoline. A 500 w high-pressure mercury lamp was used as light source for irradiation and air was introduced by a gas pump to supply O2. Thiophene dissolved in nopolar n-octane solvent was photodecomposed and removed into the polar acetonitrile phase. The desulfurization rate of thiophene in n-octane is 65.2% under photo-irradiation for 5 h. It can be improved to 96.8% by adding 0.15 g Na-ZSM-5 zeolite into 100 mL reaction system, which is the absorbent for O2 and thiophene. And the photooxidation kinetics of thiophene with O2 and Na-ZSM-5 zeolite is first-order with an apparent rate constant of 0.6305 h-1 and half-time of 1.10 h under the conditions of air flow at 150 mL-min-1 and V(n-octane): V(water)=1:1. The sulfur content can be depressed from 800 muL-L-1 to less than 26 muL-L-1.

Mixed-phase Fe2O3 was prepared from Fe(NO3)3 and (C2H5)3NHCl via solution combustion. Photocatalytic oxidative desulfurization of dibenzothiophene (DBT) under simulated sunlight irradiation using mixed-phases of α- and β-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 O2 dissolved in water. The Fe2O3 containing 36.6% β-Fe2O3 and 63.4% α-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 μg mL−1 to 44.5 μg mL−1 after 90 min. The radical scavengers experiments and terephthalic acid fluorescence technique indicated that ˙OH and O2˙− were the main reactive species in the DBT photocatalytic degradation. A potential photocatalytic desulfurization mechanism using mixed-phase Fe2O3 was proposed.

Desulfurization of dibenzothiophene (DBT) by a combination of both chemical oxidation and solvent extraction was investigated. Me3NCH2C6H5Cl·2ZnCl2 ionic liquid was prepared from cheap starting materials and used as extractant for oxidative desulfurization of DBT in n-octane. DBT in oil phase was extracted into ionic liquid phase and then oxidized to its corresponding sulfone by H2O2 and equal volume of acetic acid. The desulfurization yield of DBT in n-octane was 94% at 30 min under the conditions of H2O2/DBT molar ratio at 6 and V (ionic liquid) : V (n-octane) = 1 : 5, which was remarkably higher than that by mere extraction with ionic liquid (28.9%). The Me3NCH2C6H5Cl·2ZnCl2 ionic liquid could be recycled six times without a significant decrease in activity. Kinetics of oxidative desulfurization of DBT by H2O2 and acetic acid was first-order with an apparent rate constant of 0.0842 min−1 and half-time of 8.23 min.