Removal Of Dibenzothiophene From Model Oil By Catalytic Oxidation

With the increase of environmental protection awareness and stringent legal requirements,ultra-deep desulfurization of fuels is attracting more and more attention.Oxidative desulfurization(ODS)is often carried out at the atmospheric pressure and moderate temperature as well as without using expensive hydrogen.Besides,ODS could effectively remove aromatic thiophenes.In this research,in order to produce low sulfur oil,dibenzothiophene(DBT)was oxidized to the corresponding sulfones which are then removed by extraction.In this paper,a catalyst of molybdenum supported on modified medicinal stone(Mo/MMS)was successfully prepared by the impregnation method and characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared(FT-IR).The data show the medicinal stone had porous sponge and typical laminated structure.And the metal might has been load in the support.The results help explain the satisfactory catalytic performance.The catalytic oxidative desulfurization activity of Mo/MMS catalyst was evaluated using model oil.Comparison of four tests,when Mo/MMS catalyst was added,the removal rate of DBT was up to 96.5%,indicating that Mo/MMS catalyst displayed a very high catalytic oxidative desulfurization activity for DBT.In order to optimize catalytic oxidation conditions,the effect of different reaction parameters on the desulfurization efficiency,including reaction temperature,reaction time,the weight of catalyst Mo/MMS and the molar ratio of CYHPO/DBT were investigated.The removal rate of dibenzothiophene(DBT)reached 97.5%within 60 min under conditions of catalyst dosage of 0.50 g,reaction temperature of 100?,oxidant/sulfur molar ratio(O/S)of 5.0 and the volume of model oil of 20 ml.The higher the initial sulfur concentration in model oil,the higher the residual sulfur concentration,the more difficult for deep desulphurization.The Box-Behnken design was used to evaluate the influencs of the main operating parameters,including oxidation temperature(40??120?),oxidation time(40?80 min)and O/S(1.0?5.0)on DBT removal.The optimum values were found to be 103?,62 min and 4.0,respectively.Removal rate of DBT maximized 98.1%.Statistical results also showed the degree of importance was:O/S>oxidation temperature>oxidation time.Sulfur removal dropped to 92.2%from 98.1%to when the catalyst was reused 5 times.These results improve Mo/MMS catalyst could be cost-effective for removal of DBT from oil.