Preparation And Characterization Of Hollow Mesoporous Silica

Hollow silica is a new inorganic material with hollow structure,which not only features the excellent properties as solid silica,but also unique properties such as low density,high specific surface area and good adsorption performance.Recently,researchers have developed many methods to prepare monodisperse hollow silica with regular morphology.However,most studies focused on hollow-silica-based complexes,ignoring the exploration of synthesis methods of hollow structures.Template synthesis has attracted much attention due to its flexibility and versatility.In this thesis,the research progress of template synthesis is introduced firstly.Then the different morphology of hollow silica,including hollow sphere,hollow tube,hollow cube,etc.have been discussed.The properties and applications of hollow silica materials are list,and the future research and development of hollow silica are prospected.In this paper,the preparation of hollow mesoporous silica spheres by soft template method is studied.The results are as follows:bet multi-point specific surface area is 541.4 m²/g,single point adsorption total pore volume is 0.423 cm³/g,adsorption average pore diameter is 3.126nm,nitrogen adsorption and desorption amount is 273.4 cm³/g,and there are four characteristic absorption peaks at 461.72cm^-1,803cm^-1,1082cm^-1 and 1629.31cm^-1 in IR.In addition,SEM scanning results show that the surface morphology of the silica ball sample is needle like and high porosity.By using CTAB surfactant,the hollow mesoporous silica nanoparticles were prepared by hard template of polystyrene,as well as TEOS served as precursor.The polystyrene template has a uniform spherical shape with an average particle size of 50 nm when it is used under controlled conditions.FTIR analysis showed that the surface boundary of TEOS precursor particles was formed during the synthesis of CTAB surfactant,and the existence of Si-O-Si bond(in the range of 600-1320cm^-1).The results of thermal analysis show that organic matter can be removed from the system by proper heat treatment and synthesis of hollow mesoporous silicate particles with the smallest structural defects at 280℃.Bet analysis shows that the specific surface area of these particles is 1180m²g^-1.The results of X-ray diffraction show that the product is amorphous silica,and there is no unnecessary phase in the system.Dynamic light scattering analysis shows that the size of the synthesized particles is in the range of 1-10 nm,and the particle size distribution is in a narrow range.SEM images confirmed the nodularity of nanoparticles with an average size of25-30 nm.Finally,the TEM images show that the synthesized silicate particles are hollow particles,and the diameter and total diameter of the hollow chamber are about 30 nm and 80 nm respectively.