Construction And Oxidative Desulfurization Performance Of Immobilized Bilayer Ionic Liquid-heteropolyacid Catalysts

The sulfur oxides(SOX)produced by the combustion of sulfur compounds in fuel oil not only bring about environmental pollution such as acid rain and haze,but also seriously threaten public health.Therefore,the supply of low-sulfur "clean fuel" is still a challenge.Oxidative desulfurization(ODS)has become the most promising desulfurization technology due to its mild conditions,simple operation and high desulfurization efficiency for thiophene sulfides.Oxidative desulfurization using low-concentration H2O2 as the oxidant is expected to become an energy-saving and environment-friendly process because H2O2 is safe,non-toxicity,inexpensive,and only water as a by-product.Therefore,ODS process with H2O2 has been attracted extensive attention.The design of high-efficiency catalysts is the key issue.Focused on the construction of efficient catalyst of SiO2-bilayer ionic liquid-heteropolyacid(SiO2-BiIL-HPA)and oxidative desulfurization with H2O2 as oxidant,the thesis carried out the following two aspects of work:The catalysts of phosphotungstate immobilized on double-layered ionic liquid with N-end-capped carboxyl(SiO2-BiIL-CO2H-PW)were synthesized using SiO2 with different pore size as support.The structure and morphology of catalysts were characterized by FT-IR,XRD,SEM,TEM,XPS and other techniques.The influence of different carrier and N-capped group on the activities of catalysts was investigated in ODS process using H2Oas oxidant.The experimental results show that SiO2(50 nm)-BiIL-CO2H-PW displayed the best performance,and the sulfur removal of BT,DBT,4-MDBT and 4,6-DMDBT can be reached 100%,100%,100%and 100%,repectively.The catalysts can be easily recycled after reaction via simple filtration.There was no apparent loss of catalytic efficiency until the 4th cycle.The results show that different sulfides are oxidized to corresponding sulfones,which are the only products.The catalytic oxidation of BT follows with the pseudo first-order kinetic model.The catalysts of phosphotungstate immobilized on double-layered ionic liquid with N-end-capped sulfonate group(SiO2-BiIL-SO-PW)were prepared using SiOwith different pore size as support.The distribution of HPA,hydrophilicity/hydrophobicity,thermal stability were characterized by FT-IR,XRD,TG-DSC,BET,XPS,i.e.The characterization results demonstrate that catalytic active component are evenly dispersed on the support,and the catalyst has excellent amphiphilicity,which is the main reason for the high catalytic activity of the catalysts.The influence of different carrier on the activities of catalysts was studied in ODS process using H2O2 as oxidant.The experimental results show that using SBA-15 as carrier,the catalyst displayed the best catalytic activities.The sulfur removal of BT,DBT,4-MDBT and 4,6-DMDBT all can be reached 100%employing SBA15-BiIL-SO3-PW.Furthermore,the catalyst showed good catalytic performance in cycle experiments.