The Preparation Of Supported Polyoxometalstes Catalyst And The Study On Oxidative Desulfurization

In recent years,with the rapid progress of society and the clipping growth of economy,the frequency of using motor vehicles is getting higher and higher.However,atmospheric environmental pollution has also become serious,such as smog in cities,which has a lot to do with sulfur,nitrogen oxides and solid particulate matter produced by burning fuel containing large amounts of sulfur and nitrogen compounds.Therefore,reducing the content of sulfide in fuel has made a trouble that people need to solve quickly.At present,among many fuel oil desulfurization technologies,oxidative desulfurization technology is widely concerned by researchers at home and abroad due to its advantages such as mild reaction conditions,low investment cost,good desulfurization effect and simple operation.The focus of the oxidative desulfurization reaction is to develop a catalyst with high catalytic activity.Heteropolyacid has many advantages such as unique Bronsted acidity,excellent redox,performance adjustability and unique reaction field characteristics.The catalyst is widely used in catalytic oxidative desulfurization reaction.But its little specific surface area,easily soluble in organic solvents so that it is hard to recover.Thus,the design and development of new heteropoly acid catalysts that can enhance the catalytic performance of heteropoly acid and good recovery has become a hot spot in oxidative desulfurization.In this thesis,two series of solid polyacid catalysts for fixing heteropolyacids with cerium-doped molecular sieve MCM-41 and magnetic MOF as porous carriers were designed,synthesized,and used to study the oxidative desulfurization reaction of fuel oil.First,five kinds of metal vanadium-substituted Keggin-type phosphotungstovanadium heteropolyacids H_3+XPW_12-XV_XO40?y H₂O?X=0?4?were prepared by acidification-extraction method,and their composition and structure were used to analyze through thermogravimetry,inductively coupled plasma emission spectroscopy,powder X-ray diffraction,infrared spectroscopy and raman methods.This displays that the five kinds of phosphotungstovanadium heteropolyacids have been well prepared.Next,five synthetic phosphotungstovanadium heteropolyacids were anchored in the channel of amine-functionalized ceria doped MCM-41,and the morphology,elemental composition and structure of the catalyst were characterized by many physicochemical techniques to confirm the successful synthesis of the catalyst and used it in the catalytic oxidation reaction in fuel oil.And the catalyst PW₉V₃/APTES-Ce M-50 has 99.26%of the desulfurization rate in fuel oil under the best reaction conditions and applied continuously 8 times.Finally,using the magnetic Ui O-66 composite material as a carrier,the phosphotungstovanadium heteropolyacids are encapsulated in the pores of the magnetic Ui O-66 by a one-pot method,and the morphology,elemental composition and structure of the catalyst were characterized by many methods to confirm the successful synthesis of the catalyst and used it in the catalytic oxidation reaction in fuel oil.And the catalyst Fe₃O₄@Ui O-66-PW₉V₃ has 99.85%of the desulfurization rate in fuel oil under the optimal reaction conditions and used continuously 10 times.