Preparation And Catalytic Performance Of Nano-ceria

Considering the advantages of ceria's unique electronic effect and oxygen vacancy theory,it was used in various fields,widely.Among many preparation methods,the microemulsion method was favored by the advantages of"controllable synthesis".The conventional water-based microemulsion system will bring a lot of waste water,waste gas,waste residue pollution during the preparation and use process.In order to meet the green and clean preparation process,this topic systematically studied the preparation system of non-aqueous microemulsion nanoparticles.First,through the study of the non-aqueous microemulsion system,the ternary phase diagram of the three-component system was determined,and the suitable non-aqueous microemulsion system was selected:AEO-3/n-octane/methanol.The microstructure of non-aqueous microemulsion was determined to be W/O type by UV-Vis spectroscopy and dyeing method and the system can provide nano-droplets as micro-reactors to synthesize nano-CeO₂ particles.The optimal conditions for the preparation of nano-CeO₂ in a non-aqueous microemulsion system were determined as follows:m?AEO-3?:m?n-octane?=4:6,c?Ce?NO₃?₃?concentration 0.3mol/L,c?NaOH?concentration is 0.9mol/L and the methanol mass fraction is 14%.Nano-CeO₂,what was prepared by different methods,was compared by thermogravimetry,XRD,SEM,etc.The results showed that the nano-CeO₂prepared by the AEO-3/n-octane/methanol non-aqueous microemulsion system had a fluorite structure and high purity,and the particles were evenly dispersed.Most of them were spherical and the particle size was in the range of 10-20 nm,while the agglomeration of nano-CeO₂ prepared by hydrothermal method and direct precipitation method was relatively serious.The nano-CeO₂ prepared by non-aqueous microemulsion method,hydrothermal method and direct precipitation method was used as the carrier to prepare Ni-CeO₂ catalyst and catalyzed the methane reforming.Ni-CeO₂ catalyst was synthesized by nano-CeO₂ carrier prepared by non-aqueous microemulsion method.The experimental results showed that the Ni-CeO₂ catalyst can improve the dispersibility of nickel and had certain resistance to carbon deposition.Compared with hydrothermal method and direct precipitation method,it had more efficient catalytic and stability,and the conversion rate of methane and carbon dioxide was higher than 43%.In addition,the catalytic effect of nano-cerium hydroxide on methanol fuel was also studied.The non-aqueous microemulsion system containing nano-cerium hydroxide particles was added to methanol fuel,and it was found that methanol fuel combustion was more complete,which can significantly reduced the emission of harmful substances such as HC and NO_X in the exhaust gas,and realize the clean discharge of methanol.