Preparation And Performance Of Heteropolyacid/Activated Carbon Catalyst For Catalytic Oxidative Desulfurization

Deep desulfurization has becoming an increasingly important research subject worldwide due to increasingly stringent environment regulations.and ultra-deep desulfurization caused more attention.Hydrodesulfurization?HDS?is currently the major process for desulfurization from liquid fuels,and HDS can remove a large of sulfur in the gasoline and diesel fuel.However,the removal of thiophene is more harder,ultra-deep desulfurization process operates at severe condition,which resulted in a great loss.Therefore,new desulfurization technology drawn more attention.Among the developed alternative desulfurization technologies,oxidative desulfurization?ODS?shows great promises as it operates at mild conditions at low investment operation cost,which caused more attention increasingly.In this paper,Acidativated carbon?AC?was selected as carrier and three different heteropolyacid,including phosphotungstic acid,phosphomolybdic acid and silicotungstic acid,as active component to prepare catalysts with kegging structure by impregnation method.In addition,BET,X-ray diffractometer,FT-IR,TG-DTA and SEM were introduced to analyze surface area,pore structure,dispersed state and thermal stability of heteropolyacid/activated carbon?HPA/AC?catalyst.Thiophene and dibenzothiophene were chosen as two model sulfur compounds in gasoline and diesel fuel to study ODS of model fuel using HPA/AC catalysts with 30%H₂O₂ as oxidant and CTAB as emulsion agent.Ultimately,HPW/AC show best performance.Besides,preparation condition was optimized.The five important factors,including reaction temperature,reaction time,the mount of H₂O₂,the dosage of catalyst and CTAB on the oxidative desulfurization,were designed by orthogonal experiments and single experiments.The result shows that three HPA/ACs keep perfect keggin structure,and HPW/AC shows best performance.Phosphotungstic acid disperse on the support or into the inner hore in the form of micro-crystalline cluster.The acid strength of HPW/AC catalysts increases consequently with the increase of loading,and catalyst with 30%phosphotungstic acid supported shows best performance.ODS experiment shows that the order of influence factors for sulfur removal efficiency is:reaction temperature>the dosage of catalyst>the mount of H₂O₂>reaction time>the mount of CTAB.The optimum reaction conditons are as follows:reaction time 80 min,reaction temperature at 80?,the dosage of catalyst at 50 g/L,the molar of oxidant to surful at 12 and the dosage of CTAB at 4 g/L.The sulfur removal efficiency reached at 84.3%in gasoline model fuel and 90.4%in diesel model fuel.In addition,in this paper ODS performance of 30HPW/AC was studied in FCC gosiline and diesel fuel,and operating conditionswas optimized furtherly.Compared with sulfur type between before and after ODS,The major sulfur compounds in the gasoline are thiophene?T?benzothiophen?BT?,alkyl thiophenes,as well as small amounts of alkyl sulfides,mercaptane,thioether,etc.The results suggested higher reaction rates of BT and C3-T rather than T.By analyzed hydrocarbon components of FCC gasoline and diesel fuel,xylene,cyclohexene and octadiene were added as partial of gasoline model fuel,and xylene,naphthalene and 1,6-two methyl cyclohexene were added as partial of diesel model fuel.The result shows that the effect of model fuel composition on ODS in order as follows:cyclohexene>octadiene>xylene in gasoline model fuel and 1,6-two methyl Cyclohexene>xylene>naphthalene.Alkene,aromatic hydrocarbon and heterocyclic heterocyclic show negative effect on ODS.