Oxidative Desulfurization Process With Heteropolyacid Ionic Liquids Supported On Magnetic Core-shell Mesoporous Silicon

In recent years,the combustion of fuel has done much harm to the environment and human health.Therefore,countries in the world have established a series of standards to limit the sulfur content of fuel oil.The hydrodesulfurization（HDS）which is commonly used in industrial production has a good removal activity for thiols,thioethers and disulfides,but thiophenes and their derivatives are difficult to remove by HDS due to their electron density and steric hindrance.For this reason,non-hydrodesulfurization has been attracted more and more attention,such as extraction desulfurization,biological desulfurization,oxidative desulfurization and so on.Among them,oxidative desulfurization is known as a promising desulfurization method because of its mild reaction conditions and good desulfurization effect on aromatic sulfides.In addition,supported ionic liquid catalysts are widely used in the field of oxidative desulfurization as heterogeneous catalysts with high catalytic efficiency.In this dissertation,the ionic liquid[(C₁₈H₃₇)₂N（CH₃）₂]₃PW₁₂O₄₀ was firstly loaded onto a magnetic core-shell mesoporous carrier（MMS）by impregnation method.The catalyst was characterized by FT-IR and Raman spectroscopy.It was proved that the ionic liquid was successfully loaded,and the structure was stable before and after loading.At the same time,the transmission electron microscope（TEM）and N₂ adsorption-desorption proved the successful synthesis of the magnetic core-shell mesoporous carrier.The synthesized catalyst[(C₁₈H₃₇)₂N（CH₃）₂]₃PW₁₂O₄₀/MMS was used for deep oxidation of fuel.Under the optimal conditions,96.3%of4,6-DMDBT could be removed within 120 min.The catalyst could be easily separated and recycled for 7 times.The oxidative product was analyzed by FT-IR spectroscopy after the reaction.4,6-DMDBTO₂ was found with the help of FT-IR as the oxidization product of 4,6-DMDBT,and the catalytic reaction process was inferred.Due to the strong hydrophilicity of carrier magnetic mesoporous silicon（MMS）,the contact between the catalyst and the oil is insufficient.Therefore,the hydrophobicity of the carrier is improved in order to obtain a faster reaction rate.The ionic liquid[（C₄H₉）₃NCH₃]₃PMo₁₂O₄₀ was loaded onto two kinds of magnetic core-shell mesoporous carriers with different surface wettability by impregnation method,respectively.The ionic liquid was proved to be successfully loaded by characterization and the structure was stable.The contact angles demonstrated that RS-MMS has a better hydrophilic-hydrophobic balance than SS-MMS.The obtained catalyst was used in the oxidative desulfurization of fuel.The experimental results showed that the catalyst[（C₄H₉）₃NCH₃]₃PMo₁₂O₄₀/RS-MMS had better activity than the catalyst[（C₄H₉）₃NCH₃]₃PMo₁₂O₄₀/SS-MMS.Under optimal reaction conditions,the catalyst[（C₄H₉）₃NCH₃]₃PMo₁₂O₄₀/RS-MMS could achieve 100%removal of4,6-DMDBT within 50 min.The catalyst was easy to be separated and circulated for 5times.In the oxidative desulfurization reaction,the choice of oxidant is a very important part.In the early stage of oxidative desulfurization,H₂O₂ was mostly used as an oxidant.But H₂O₂ is inconvenient to transportation and storage due to its instability.At the same time,the reaction may cause biphasic problems,which have a certain influence on its industrial application.Oxygen has attracted more and more researchers’attention due to its low cost,easy availability and safety.In the experiments,the ionic liquid[(C₈H₁₇)₃NCH₃]₃PMo₁₂O₄₀ was loaded onto a magnetic core-shell mesoporous supporter（γ-MMS）by impregnation method.The catalyst[(C₈H₁₇)₃NCH₃]₃PMo₁₂O₄₀/γ-MMS was used for the catalytic oxidation desulfurization with oxygen as the oxidant.Under optimal conditions,the DBT can be removed by 100%within 5 hours.The catalyst could be easy separated and still have a better desulfurization effect after 5 cycles.The product after catalytic reaction was analyzed by infrared and mechanism of the oxidative desulfurization of catalyst[(C₈H₁₇)₃NCH₃]₃PMo₁₂O₄₀/γ-MMS with oxygen was investigated.