Synthesis Of Organic-inorganic Polyox-ometallate Hybrid And Its Application In Oil Desulfurization

The combustion of sulphur-containing fuels produces a large amount of harmful substances,causing environmental problems such as smog and acid rain.The quality requirements of oil products in various countries around the world are constantly im-proving,and producing low sulfur content oil products has become a global trend.Therefore,the development of efficient and clean oil desulfurization technology has be-come a research hotspot in recent years.Oxidative desulfurization technology(ODS)received extensive attention due to its mild reaction conditions and the advantages of deep desulfurization.As a catalyst commonly used in oxidative desulfurization,polyoxometallate(POM)has been extensively studied due to its high catalytic activity,wide variety,adjustable redox property,diverse structure and strong adjustability.However,it mainly suffers from poor amphiphilicity,high solubility in polar solvents,and large mass transfer re-sistance,which limit its further application.By means of ionic assembly and covalent modification of polyoxometalate,highly efficient heterogeneous catalysts with stable chemical structure,regular morphology,easy recovery and separability were prepared.A novel and precise ionic self-assembly(ISA)construction strategy for the self-assembly of polymeric quaternary ammonium salts(polyionene)and Anderson-type polyoxometalate(?-Mo₈O₂₆^4-)to form a three-dimensional nanoflower structure was developed successfully and used for oxidative desulfurization(ODS)of fuels for the first time.Furthermore,the morphologies of the self-assembled structures could pre-cisely regulated by varying the reaction conditions,including the concentra-tions of the polyionene and temperature.Additionally,the nitrogen sorption analysis indicated its porosity with a surface area up to 140 m²g^-1.Remarkably,the nanoflow-ers showed excellent conversion(98.9%)towards oxidative ODS process with six times recycle.This could be ascribed to the large amount of active sites dispersed over the relatively high specific area,providing contact with reactants in(ODS)process.As a follow-up study to prepare catalysts with higher amphipathicity,a highly ef-ficient phase transfer catalyst was prepared by using a heteropolyacid catalyst in which tris covalently modified,and using surfactant ions as counter ions.The oxidative desul-furization performance of the catalyst in the model oil was studied,and the reaction conditions were optimized.When the reaction temperature was 50°C,O/S was 6,and the catalyst dosage was 30 mg,the DBT con-version rate reached 99.9%.Its desulfuri-zation performance with real diesel was also analyzed to predict the potential for further industrialization.