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Application Of Supported Heteropoly Acid Catalyst In Oxidesulfurization

Posted on:2014-06-28Degree:MasterType:Thesis
Country:ChinaCandidate:G Q LuoFull Text:PDF
GTID:2181330467459727Subject:Chemical engineering
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The sulfur content (S-content) in fuel oil, which not only damages the engine, but also generates seriousair pollution during combustion due to SOxemission. Recent years, the problem are becoming increasinglystringent worldwide, so many countries have legalized stern environmental regulations to control fuelS-content. Currently, oil sulfur content is treated and removed by hydrodesulfurization (HDS) process forindustrial purpose. However, In order to reach a satisfactory level of sulfur removal requires hightemperature and high pressure (up to100atm). Moreover, it is difficult to remove some heterocyclic sulfurcompounds such as dibenzothiophene (DBT) and its derivatives which are major sulfur content in fuel oil.Therefore, researchers have committed to develop new desulfurization process. Among these methods,oxidesulfurization (ODS) process is considered as the most promising and economical for ultra-deepdesulfurization of fuel oils, because of its high desulfurization efficiency, moderate reaction conditions, lowoperating cost and simple technical process.In this paper, we prepared and studied some supported phosphotungstic acid catalysts based on works ofprevious researcher and our group.(1) HPW-PDMAEMA-SiO2(HPW represented phosphotungstic acid, PDMAEAM represented poly-N,N-dimethylaminoethyl methacrylate) catalyst was sucessfully synthesized. The obtainedHPW-PDMAEMA-SiO2catalyst was characterized by X-ray diffraction (XRD), transmission electronmicroscopy (TEM), Fourier transform infrared spectra (FTIR), thermo-gravimetric analysis (TGA) andinductively coupled plasma atomic emission spectroscopy (ICP-AES). The results demonstrated that HPWactive species retained its Keggin structure after immobilizing on polymer brushes. The optimal reactioncondition for oxidative desulfurization of dibenzothiophene was investigated. Under the optimal reactionconditions: reaction time was2.5h, the catalyst dosage was0.1g/10ml oil, O/S=12, T=333K, the ODSconversion of DBT reached up to100%, and no significant catalytic performance decreased after sixrecycles. It was supposed that the excellent recover ability of HPW-PDMAEMA-SiO2catalyst wasattributed to the reduced leaching of HPW active species in ODS process, due to the strong interactionbetween [PW12O40]3-negative ion and ammonium positive ion in PDMAEMA polymer brushes.(2) Phosphotungstic acid H3PW12O40(HPW) was successfully immobilized on the surface of MCM-41functionalized with amino groups (NH2-MCM-41). The obtained catalysts were characterized by XRD,TEM, FT-IR, TGA, andICP-AES. The results indicated that the surface area of MCM-41support decreasedafter it was functionalized with amino groups, whereas the HPW active species retained its Kegginstructure. HPW-NH2-MCM-41exhibited excellent catalytic performance for oxidesulfurization ofdibenzothiophene. Under optimal conditions: reaction time was2.5h, the catalyst dosage was0.02g/10mloil, O/S=8, T=333K, the conversion of DBT reached up to100%. The catalyst could be recycled fivetimes without any significant loss of catalytic activity. The excellent recyclability was attributed to thestrong interaction between the amino groups and the HPW species.(3) Mesoporous silica pillared clay (SPC) materials with different contents of H3PW12O40heteropoly acid were synthesized by introducing HPW into clay interlayer template in an acidic suspension using sol-gelmethod. The results of the characterizations showed that HPW was dispersed in the encapsulated samples.The encapsulated materials exhibited high catalytic performance. The sulfur removal reached up to100%for the model oil under the experiential conditions: reaction time was2.5h, the catalyst dosage was0.04g/10ml oil, O/S=10, T=333K, and no significant catalytic performance decreased after five recycles.
Keywords/Search Tags:Oxidesulfurization, Phosphotungstic acid, Poly brush, Mesoporous materials, Hydrogenperoxide
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