Oxidative Desulfurization Catalytic Performance And Immobilization Mechanism Of Phosphotungstic/Mesoporous Materials Catalysts

In 21st century, the regulations for diesel fuel sulfur require more stringent restrictions and the low sulphur diesel is demanded enormously on the market, so major petrochemical enterprises and scientific research institute in the world all take up with the development of various technologys of diesel oil desulfurization. The technologys of diesel oil desulfurization main includ hydrodesulfurization(HDS) and non-hydrodesulfurization. HDS is a mature technology and is used widely in diesel oil desulfurization,but this technology has some disadvantages, such as large investment, high operating costs. At the same time, the regulations for diesel fuel sulfur are increasingly harsh,the technology of hydrodesulfurization can not meet the demand of diesel oil desulfurizat. The technology of oxidative desulfurization can be run in the room temperature and can catalyze the oxidation reaction for dibenzothiophene in diesel oil which is removed difficultly by the technology of hydrodesulfurization, simultaneity, this technology need a little investment.In this paper, on the basis of the understand for the research on the catalytic properties and application of heteropoly acid, the author researchs the synthesis of heteropoly acid with high catalytic activity/mesoporous silicates composition, immobilization mechanism and the effect of immobilization methods on catalytic properties. Then the author designs and synthesizes heteropoly acid with high catalytic activity/mesoporous composition and applly it to the research on oxidative desulfurization of macromolecule organic sulfide in diesel. The fruits of this paper are as follows:1.The catalytic properties of HPW/Amino/SBA-15 which is synthesized by amino-functionalized method have been researched. Then the immobilization mechanism of HPW as well as the relationship between catalytic properties and immobilization mechanism have been discussd. The results show that the catalyst has higher catalytic activity and higher catalytic stability as result that HPW is evenly distributed on the surface of the mesoporous walls and there is the stronger HPW immobilization force between HPW and supports. 2.The catalytic properties of HPW/EISA/p6mm mesoporous SiO₂ which is synthesized by evaporation-induced self-assembly method, have been researched. Then the immobilization mechanism of HPW as well as the relationship between catalytic properties and immobilization mechanism have been discussd. The results show that the catalyst has higher catalytic activity and higher catalytic stability as result that HPW is evenly encapsulated into the framework of the mesoporous walls and there is the stronger HPW immobilization force between HPW and supports. The immobilization forces are from the chemical bonds formed by the polycondensation reaction between OH groups on HPW molecules and Si-OH groups, and the hydrogen bonds between W=O groups on HPW molecules and Si-OH groups.3.HPW/HOM-5 is synthesized by direct-templating synthesis method. HPW is evenly encapsulated into the framework of the mesoporous walls and the Keggin structure of HPW is preserved. The supports have three-dimensional (3D) bicontinuous channels. The author takes oxidation reaction of DBT for example to compare the catalytic performance of HPW/HOM-5.The results show that the catalyst has higher catalytic activity and higher catalytic stability. The first percent conversion of DBT is 99.5% within three hours, and after seven usages, that could be 96.4%.4.HPW/mesoporous TiO₂ is synthesized by evaporation-induced self-assembly method. The supports have p6mm channels. The author takes oxidation reaction of DBT for example to compare the catalytic performance of HPW/mesoporous TiO₂.The results show that the lower catalytic activity of HPW/ mesoporous TiO₂ than that of HPW/H0M-5. The reason is that the Keggin structure of HPW is destroyed because the wall of supports forms crystal. The first percent conversion of DBT is 92.7% within three hours, and after seven usages, that could be 87.2%.This indicates that this catalyst still have higher catalytic stability.