Preparation And Catalytic Oxidation Desulfurization Performance Of Rare Earth Modified Polyacid Catalyst

With the increasing of the society progress and the leapfrog development of science and technology,People’s Daily life and travel production requirements increasingly dependent on fuel,fuel composition of particularly sulfur dioxide(SO2)and its derivatives,can cause chain reaction to environmental harm,and more may do harm to human health.Therefore,all countries in the world to the fuel sulfur content requirements are more and more stringent standards,the production of ultra-low or even "zero" sulfur green fuel has become an inevitable trend.Oxidative desulfurization(ODS)technology with its mild reaction conditions,less equipment investment,no need for hydrogen source,normal temperature and pressure can meet the reaction,and hydrodesulfurization(HDS)is difficult to remove benzothiophene compounds with a high removal rate,so that it stands out in many desulfurization technology.Catalysts usually speed up the process of oxidation and desulfurization reaction,so the selection of a good catalyst plays a crucial role in the desulfurization effect of fuel.In recent years,HPCs,as a new type of multifunctional catalyst,has attracted extensive attention due to its excellent catalytic performance.In this study,new multi-acid catalytic materials with different structures and highly recoverable complex heteropolyphal compounds were prepared as catalysts The main research contents are as follows:Through the step by step reaction,fractional acidification method,two kinds of heteropoly acid silicon molybdenum vanadium and tungsten,vanadium,silicon was prepared by changing the ratio of raw materials of eight different vanadium content in silicon molybdenum vanadium(H5SiMo11VO40,H6SiMo1OV2O40,H7SiMo9V3O40,H8SiMo8V4O40)and silicon tungsten vanadium(H5SiW11VO40,H6SiW10V2O40,H7SiW9V3O40,H8SiW8V4O40)precursor,and acid catalyzed by rare earth modification is made much more material,and comprehensive characterization of the catalyst.The catalytic activity of rare earth modified polyoxometalate catalysts was investigated,and the best catalysts were CeH3SiMo10V2O40 and LaH5SiW8V44O40.CeH3SiMo10V2O40 and LaH5SiW8V4O40 were used as catalysts,H2O2 was used as oxidant,and acetonitrile was used as extractant.The experimental results showed that using CeH3SiMo10V2O40 as catalyst,Under the following conditions,the amount of catalyst accounted for 0.25%of the simulated oil mass,the ratio of oxygen to sulfur was 10,the precontact time of catalyst and H2O2 was 8 min,the reaction temperature was 60℃,and the initial sulfur content was 500 mg/kg.When the reaction lasted for 180 min,the sulfur compounds were completely removed.Using LaH5SiW8V4O40 as catalyst,under the conditions of time to 180 min,Dibenzothiophene(DBT)conversion rate of 99.58%.The amino composite catalysts(NH4SiWV-SiO2 and NH4SiMoV-SiO2)were prepared by dispersive polymerization of hollow SiO2 particles as supporting materials.The catalytic desulfurization performance of the two supported catalysts in the oxidation desulfurization system was investigated.The experimental results show that the catalytic performance of NH4SiWV-SiO2 is better,and the comprehensive characterization of the catalyst was carried out.NH4SiWV-SiO2as catalyst,H2O2 as oxidant,acetonitrile as the extractant,the best catalytic conditions:catalyst accounts for 0.5%of the simulated oil quality,oxygen,DBT content in 5.3 mg/kg,DBT removal rate can reach 98.94%.The catalytic performance of NH4SiWV-SiO2 is still good after being reused for 5 times.Three optimal catalysts,CeH3SiMo10V2O40,LaH5SiW8V4O40 and NH4SiWV-SiO2,were used to investigate the desulfurization performance of real fuel under their optimal catalytic conditions.The structure shows that the three catalysts have good desulfurization effect on the real fuel,and the sulfur content in the fuel can meet the latest national sulfur content standard after continuous extraction.The kinetics of DBT oxidation desulfurization reaction was studied,and the apparent reaction order was determined to be first order.The reaction mechanism of catalytic oxidation was studied by fourier infrared spectroscopy(FR-IR)and liquid-mass combination(LCMS).Through the study,it was found that the heteropoly acid catalyst was first oxidized by H2O2 to form a peroxy anion,which has a strong oxidation ability.The sulfide was oxidized into a sulfone,and the sulfone was the only product after oxidation.Finally,it was extracted by the extraction agent acetonitrile,which realized the removal of sulfides in the oil through oxidation reaction.