The Oxidative Desulfurization Of Dibenzothiophene With Non-water-soluble Oxidants

Dibenzothiophthene derivatives are the stablest organic sulfur containing compound in fuel oils, their oxidative desulfurization is of great importance to the deep desulfurization technology. The oxidation of dibenzothiophene (DBT) is performed with molybdenum oxide catalysts using tert-butylhydroperoxide (TBHP) as oxidant, and metalloporphyrin catalysts using tert-butylhydroperoxide and oxygen as oxidants in this paper. Both achieve good conclusion.The synthesis of TBHP is conducted throuth investigating effects of reactants adding sequence, reaction temperature, reaction time and reactants mole ratio, and the optimal reaction condition is obtained. The yield of TBHP is improved, the reaction time is shortened and the effective content of TBHP is increased to 95.7%.The oxidation of DBT in decalin solvent is performed with oil-soluble TBHP as oxidant in the presence of supported MoO₃ catalysts. Effects of reaction temperature, reaction time, oxidant amount and catalyst amount are investigated in detail and the optimal oxidative condition is achieved through orthogonal and single factor experiments. The conversion of DBT is up to 99.8%, and the selectivity of the catalysts is also investigated. It is concluded that D751 and D113 enlarge the contact area between MoO₃ and TBHP, enhance the catalysts activity and reduce the catalysts amount obviously. After used for 10 times, the catalysts still have good activity. MoO₃/D751 catalyst has a better stability and activity, and MoO₃/D113 catalyst has a better selectivity. The mechanism is then disscussed.Oxidative of DBT is also investigated using TBHP and O₂ over four different kinds of metalloporphyrin catalysts, TPPMn, TPPFe, TClPPMn and TClPPFe. The factors of reaction temperature, reaction time, oxidant amount and catalyst amount are investigated in detail and the optimal oxidative condition is obtained. The conversion of DBT is up to 99.8% and the activities of metalloporphyrins decrease in the order TClPPMn > TClPPFe > TPPMn > TPPFe. The mechanism is then disscussed.