Catalytic Oxidative Desulfurization Process In Fuel Oil With POM-based Ionic Liquid And Its Polymer

With the continuous progress and development of society,fuel oil is increasingly indispensable in daily life and production activities.However,the burning of sulfides in fuel oil will release SO_x,one of the culprits of environmental problems,causing acid rain and haze,which will seriously influence human health and ecological environment.At present,the traditional hydrodesulfurization technology,which requires high temperature and high pressure,is not suitable for long-term stable development in industry.Therefore,non-hydrodesulfurization technologies have become the focus of research.Among them,oxidative desulfurization has attracted widespread attention due to its mild reaction conditions and high desulfurization efficiency.In this thesis,a series of POM-based ionic liquids and their polymers have been prepared by modifying the anion-cation and anion-exchange methods.It is applied to the oxidative desulfurization of fuel oil,and its structural properties are analyzed by means of FT-IR,XPS,XRD and other characterization methods.First,different vanadium-substituted heteropolyacids with Keggin structure were synthesized by stoichiometry,and then immobilized on imidazole-type ionic liquids by anion exchange to form molybdovanadophosphoric-based imidazole ionic liquid catalyst[C₄VIM]PMoV₂.Combined with characterization technology,experimental data and theoretical calculations,it is proved for the first time the important role of vinyl functional groups on cations in ionic liquids during the catalytic reactions.In the desulfurization system using oxygen as the oxidant,the optimal desulfurization conditions are tested?the reaction temperature is 120^oC,the air flow is 100 mL/min,the amount of catalyst is 0.05 g,and the stirring speed is 1000 rpm?.Under the best reaction conditions,the desulfurization rate can reach 98%in 5 hours.The removal order of different sulfur-containing substrates was DBT>4-MDBT>4,6-DMDBT,and the catalyst could be recycled for 6 times without significant decrease in activity.Secondly,by anion exchange method,as an active center,the vanadium-based homopolyacid anion is combined with poly?ionic liquids?,which contain different carbon chain length,to form a poly-vanadate-based poly?ionic liquid?catalyst p-C₄VIM-V10.Through various characterization techniques and experimental data,it is proved that the catalyst is successfully prepared with excellent stability and catalytic oxidative desulfurization activity.In the desulfurization system using oxygen as the oxidant,the optimal desulfurization conditions are tested?the reaction temperature is120^oC,the air flow is 100 mL/min,the amount of catalyst is 0.05 g,and the stirring speed is 1000 rpm?.Under the best reaction conditions,the desulfurization rate can reach 98%in 3 hours,which further shortens the reaction time.The removal order of different sulfur-containing substrates was DBT>4-MDBT>4,6-DMDBT,and the catalyst could be recycled for 10 times without significant decrease in activity.Finally,in order to further decrease the reaction conditions,the ionic liquid and DVB are crosslinked and copolymerized into a poly?ionic liquid?copolymer with a higher specific surface area,and combined with phosphomolybdic acid?CP grade?by anion exchange to form POM-based poly?ionic liquid?catalyst p-C₂VIM-DVB-2-PMo.In the desulfurization system using hydrogen peroxide as the oxidant,the optimal desulfurization conditions are tested?the reaction temperature is 40^oC,the molar ratio of oxygen and sulfur is 5,the amount of catalyst is 0.01 g,and the stirring speed is 1000rpm?.Under the best reaction conditions,the desulfurization rate can reach 95%in 2hours.The removal order of different sulfur-containing substrates is 4,6-DMDBT>DBT>4-MDBT.The catalyst could be recycled for 8 times without significant decrease in activity.