Preparation And Characterization Of Microporous And Mesoporous Materials With Core-Shell Structure

Core-shell nano-material is a hot topic in modern material science, the material with functional group or nano-pore structure can be composited by core-shell type. SiO2 sphere plays an important role in research history of core-shell nanoparticles, which can be used as shell and hard template.the advanced stage of development of silicon is the zeolite, its contribution to the industry catalysis is very great, titanium silicalite TS-1 has been developed in recent years, researchers pay close attentions to it because of its outstanding catalysis results for environment friendly oxidation, the development of porous silicon boost the development of mesoporous carbon materials, carbon material has some excellent features, such as high hydrophobicity, large surface area, etc. So the research of silicon and carbon composite material has been started, but most of the research on the idea of this material is embedding silicon in the carbon materials to make dispersed composite material of carbon and silicon, while the real synthesis method of carbon and silicon core-shell materials with ordered structure is reported rarely. Therefore, the main aim of this work is to design and synthesize carbon-silicon core-shell material, which core phase is TS-1 or SiO2 nano-sphere and shell phase is mesoporous carbon. The work includes the following four parts:1,Synthesis and characterization of nSiO2@mesoC core-shell materialSiO2 sphere with uniform size has been prepared using Stober method. Dispersing the spheres in alcohol, water and ammonia mixture system, using CTAB as template agent, mesoporous SiO2 were grew on the core successfully. It could obtain meso-carbon after filling the mespors with carbon source and replicating the hard template. The samples were characterized by XRD, SEM, TEM techniques. It proved that the material was composite nanoparticle with core-shell type and meso-carbon shell.2,Investigation of synthesis conditions of nSiO2@mesoC core-shell materialIt was investigated firstly how the mass of ammonia in the system to affect the diameter of SiO2 sphere, and then other factors were investigated on the impact of material preparation, such as diameter of the core, shell thickness and the concentration of HF acid. It could be seen from the results that every process was interactive in material preparation, especially the control of HF concentration was essentially important on the formation of silicon-carbon core-shell materials.3,Synthesis and characterization of TS-1@mesoC core-shell materialTS-1 nano-particle with uniform diameter was obtained applying traditional hydrothermal synthesis method. Through the same processes, TS-1@mesoC could be prepared, the sample was composite nanoparticle, which owned core-shell morphology and the shell was mesoporous carbon.4,Investigation of synthesis conditions of TS-1@mesoC core-shell materialIt was investigated firstly the synthesis of TS-1 with different diameter and different Si/Ti ratio, and then other factors were investigated on the impact of the material preparation. The possibility of TS-1 resistant to HF was stronger than mesoporous SiO2, it laid the foundation to prepare the materials successfully.