Magnetic Supported Transition Metal Oxide Catalysts For Oxidative Desulfurization Of Fuels

With the continuous increase of car ownership,environmental pollution has become more and more serious.The sulfur oxides?SO_x?generated by fuel combustion have seriously polluted the environment and endanger the human health significantly.Moreover,the SO_x produced by combustion will reduce the catalytic ability of the catalyst in the vehicle exhaust treatment device.As a result,many countries have enacted corresponding environmental regulations and issued strict emission standards to reduce the content of sulfur-containing pollutants produced by fuel combustion.Deep desulfurization of liquid fuel is an important subject in the theoretical and practical application aspects.To deal with these problems,various desulfurization technologies have been used to reduce the sulfur content in the fuel oil.Among of them,non-hydrodesulfurization technologies are more widely studied by researchers because of its mild reaction conditions and good removal effect on aromatic sulfide.In this paper,the magnetic supported metal oxide catalyst was designed and synthesized,which was applied to the catalytic oxidation desulfurization research system.The removal effect of the catalyst on the sulfide in fuel was investigated,and the desulfurization reaction process was analyzed and the reaction mechanism was further explored.1.The magnetic material was synthesized by sol-gel method,and the active component was loaded onto magnetic silica?MS?by impregnation method.The heteropolyacid ionic liquid[C₄mim]₃PMo₁₂O₄₀ was used as the molybdenum source and the final catalyst MoO₃/MS-400 was obtained by calcination method.The structure and composition of the catalyst were analyzed by a series of characterization.The catalysts treated with different calcination temperatures were applied to the sulfur removal research system of fuel and the desulfurization performances were investigated.Under the optimal reaction condition,the desulfurization rate of DBT reached 100%,meeting the requirements of deep oxidation desulfurization.Finally,the catalyst can be separated from the reaction system quickly under the existence of external magnetic field.2.The choice of oxidant is an important part in the chemical reaction process.Hydrogen peroxide?H₂O₂?as oxidant had safety problems in transportation.And the two-phase problem caused by H₂O₂ in the process of reaction led to poor oxidation effect and other problems.So low-cost,safe and easily available air was used as oxidant in this system.In addition,due to the small specific surface area of carrier MS,the active components are not easy to be evenly dispersed,resulting in insufficient contact with oil.Therefore,magnetic mesoporous silica layer mesoporous?MMS?is synthesized as the carrier to increase the specific surface area.In this experiment,magnetic carrier MMS was synthesized by sol-gel method and template method.H₃PW₁₂O₄₀·26H₂O?HPW?was used as tungsten source and HPW was loaded onto MMS by impregnation method.Finally,the catalyst WO_x/MMS-500 was obtained by calcination method.The structure analysis of the catalyst was carried out by various analytical methods.It was applied to the catalytic oxidation desulfurization system to activated oxygen.It was found that the catalyst can remove DBT at 120°C for 8 h and99.9%of sulfur removal was reached.Finally,it was confirmed by GC-MS analysis that the reaction product was DBTO₂ and the reaction mechanism was discussed.3.Due to the strong hydrophilicity of the carrier MMS,the contact between the catalyst and the model oil in the reaction system was insufficient.Therefore,the rate of oxidative desulfurization reaction is enhanced by altering the hydrophobic and lipophilic nature of the catalyst.In this experiment,magnetic nanoparticles were synthesized by sol-gel method,and then magnetic polymer was synthesized by addition polymerization.H₃PMo₁₂O₄₀·14H₂O was used as molybdenum source.The active component was loaded onto the magnetic polymer carrier by impregnation method and then it was calcinated.The composition and structure of the catalyst were analyzed by a series of characterization methods.The contact angle experiment proved that the catalyst MoO_x/MC-600 had better hydrophilic and hydrophobic properties.Finally,the catalyst was used in the system of activated oxygen catalytic oxidation desulfurization.Deep desulfurization of sulfide DBT could be completed within 4 h at the reaction temperature of 120^oC.And the desulfurization rate was97.1%.The recycled performance of the catalyst showed that the removal efficiency of sulfur did not change significantly after recycled 7 times,indicating excellent cyclic performance of the catalyst.