Preparation Of Hierarchical Nanostructured Functional Materials And As Support For Catalysis

Hierarchical porous materials have the characteristics of high surface area,large accessible space,low density,easy to synthesis,and easy to functionalize.Driven by the multi-scale structure,people combine the primary hierarchical pore structure with the secondary structure of different length scales to make binary hierarchical pore materials with more structural advantages.The binary structure makes the material have more excellent characteristics,solves the inherent defects of many materials,and makes the application of hierarchical pore materials more widely.The main research contents and results are as follows:(1)To construct secondary processes of multiscale architecturing,wrinkly silica microspheres(WSMs)are nested into the empty chamber of templated macroporous structure by using core–shell microspheres to self-assemble the colloidal crystal template and selectively removing the shells.It is a universal approach to form the binary inverse opal(IO)structures and maintain interconnected nanochannels.With gold nanoparticles loaded on the WSMs(denoted Au-WSMs@IO SiO₂)in the meantime,the binary IO material(Au-WSMs@IO SiO₂)completed the catalysis in 4 minutes in the reduction of 4-nitrophenol(4-NP).After 15 cycles,Au-WSMs@IO SiO₂ had higher catalytic efficiency than simple nested microspheres(Au-WSMs).Furthermore,it also showed good catalytic performance in the epoxidation of styrene.The conversion of styrene was as high as 89.83%.The binary IO material can effectively protect the noble metal nanoparticles,reduces their aggregation and loss,and ensure excellent catalytic performance.The integrated structure makes it recyclable and mechanically stable.Therefore,it will be a promising way to widely apply in heterogeneous catalysis.(2)In order to solve the inherent defect of low specific surface area of 3DOM materials,toluene was used as the porosity,and micropores were introduced into the 3D ordered macroporous crosslinked polystyrene(3DOM CLPS)to obtain a macroporous-microporous crosslinked polystyrene(HP CLPS)with high specific surface area.The specific surface area and pore volume of HP CLPs increase with the increase of crosslinking degree,while the pore size decreases.HP CLPS was sulfonated using acetosulfonate as a sulfonating agent to have a sulfonic acid group,and it was found that an increase in the degree of crosslinking caused a reduction in sulfur content.When HP CLPs with sulfonic acid group was used as solid acid,it showed good catalytic activity in ketalization of cyclohexanone with glycol and esterification of oleic acid with methyl ester.(3)A simple method was used to prepare a unique structure of hierarchical pore silica(HP SiO₂)microcapsules.Only the sulfonated 3DOM polydivinylbenzene(PDVB)was used as a hard template.Tetraethyl orthosilicate(TEOS)was hydrolyzed at the sulfonic acid site to form HP SiO₂ microcapsules.In essence,HP SiO₂ microcapsules replicated the macropore of 3DOM,so pore windows are formed on the microcapsules.The most unique is that HP SiO₂ microcapsules have ordered array of radial hole channels which can be seen from the scanning electron microscope photograph of ultra-thin sections of the material.