Study On Green Synthesis And Catalytic Performance Of Dendritic Mesoporous Nanoparticles

The mesoporous silicon material has attracted much attention due to its excellent pore structure,large specific surface area and special surface properties.It provides the carrier for biological and industrial applications and opens the door to the func-tional materials of the loaded macromolecules.Mesoporous silicon nanoparticles with size less than 200 nm has attracted wide attention due to the short diffusion path and easy reaction center.In this paper,based on the existing research on the synthesis of dendritic mesoporous materials,we prepared the dendritic mesoporous silica nanopar-ticles with different co-surfactants according to their synthetic mechanism.compared these silica nanoparticles loaded with different activity sites and the conventional mesoporous material MCM-41 in the performance of catalytic reaction.In the first part,the dendrimer mesoporous silica nanoparticles were successfully prepared by adding dicarboxylate with different carbon chain length as co-surfactant and cetyltrimethylammonium bromide as surfactant.When changing the length of the carbon chain of the co-surfactant,the size of the nanoparticles can be finely regulated and the degree of opening of the dendritic channels can be adjusted too.Moreover,in the range of experimental investigation,the longer the co-surfactant carbon chain is,the more obvious the dendritic pore structure is.On the basis of the first part,in the second part of the article,we synthesize the titanium-containing silica nanoparticles with the dendritic pore structure by one step introducing the titanium source in the synthesis process.The degree of opening of the dendritic pore can also be adjusted by increasing the length of the carbon chain of the co-surfactant.As the transition heteroatom is easy to hydrolyze,we also compare TDA to TBOT as titanium source with different hydrolysis rates prepare dendritic ti-tanium nanoparticles for epoxidation of cyclohexene.Compared with Ti-MCM-41,the catalytic activity of Ti-DMSNs are similar to that of Ti-MCM-41,and the TON was higher than that of Ti-MCM-41,which made the titanium resource used effi-ciently.In addition,we also study the relationship between catalytic activity and tita-nium source species and co-surfactant.We investigated the effect of titanium source hydrolysis rate and the length of the carbon chain of the co-surfactant on the catalytic performance of the catalyst.In the third part,we try to synthesize dendritic mesoporous silica nanoparticles with 'no-alkali' method.We can successfully synthesize dendrimer silica nanoparti-cles with co-surfactant without adding alkali by this method.Simple operation,lower cost,lower pollution,meeting the environmental protection and sustainable develop-ment requirements are the advantages of this method.The silver-containing nano-catalyst prepared by this method is subjected to the oxidation experiment of benzyl alcohol,and its reaction performance is slightly higher than that of the conven-tional catalyst.