The Research Of Oxidation Reactions Of Sulfur Containing Compounds By Air

The oxidation reaction of dibenzothiophene (DBT) and dimethyl sulfoxide(DMSO) were investigated in the paper. DBT and its derivatives are the common sulfur containing compounds in fuel, which are the most unreactive sulfur compounds during HDS and the major factor limiting deep desulfurization of HDS method. Through oxidation reaction, DBT is oxidized to the corresponding sulfone which has higher polarity than itself, so it can easily be removed by extraction from fuel and deep desulfurization was realized. Oil soluble oxidant cumene hydroperoxide (CHP) and air were used as oxidants for DBT, DMSO respectively. The oxidation products were DBT sulfone and dimethyl sulfone.Catalytic oxidation of dibenzothiophene (DBT) in decalin was performed in a fixed bed glass reactor using an oil-soluble oxidant, cumene hydroperoxide (CHP), over MoO3/SiO2 catalyst. The conversion of DBT reached 82%. To improve the reactivity MoO3/SiO2 catalyst, alkaline earth metals, such as CaO, BaO, SrO and MgO were introduced to modify MoO3/SiO2 by a two step impregnation method. The results showed that the activity of CaO and BaO modified MoO3/SiO2 catalyst have higher activity than MoO3/SiO2 in the oxidation of DBT with CHP and the MoO3/Ca-SiO2 catalysts has best activity. The DBT conversion reached 94% at 60℃.Based on the fact that hydrocarbon compounds can be autoxidized to corresponding hydroperoxide slowly by oxygen in air, the oxidations of DBT in decalin or n-octane toluene were respectively performed by the air/Ti-MCM-41 system in the presence of AIBN or BPO. The conversion of DBT can reach 100% when using decalin or n-octane as solvent; while the conversion of DBT can reach only 83% when using toluene as solvent at the same condition. This difference was result from the different auto oxidation speed of organic molecule.Cumene was oxidized to corresponding hydroperoxide at 70℃in the presence of free radicals decomposed from AIBN. DMSO can be oxidized to dimethyl sulfone by the obtained hydroperoxide on ammonium metavanadate catalyst. The reaction condition were as follows: 3 mL DMSO was added to 20 mL cumene,70℃,180 min, dosage of catalyst 0.3 g, dosage of AIBN is 0.4 g, feeding mode of DMSO is dropping. The conversion of DMSO is 94%.