Preparation And Characterization Of Hexagonal Mesoporous Silica (HMS)

Mesoporous materials have many potential applications in chemical industry, information technology, biology technology and environment energy sources due to their various components, large specific surface area and uniform mesoporous structure. Pore size modification is one of the most important aspects in the preparation and application of mesoporous sieves, because it sifting on the molecular level could be achieved by mediating the pore size.The influence of preparing conditions such as reaction temperature, reaction time, the amount of cosolvent, the amount of solvent, the removal methods of the template and temperature of calcinations on structure of HMS were discussed. The structures of the materials were investigated by X-Ray Powder Diffraction (XRD), N2 adsorption-desorption isotherms, High-Resolution Transmission Electron Microscope (HRTEM).The experimental results suggested that the pore size increased with reaction temperature increase, while first increased then decreased with increasing either water or ethanol, but remained with reaction time varing. The template was eliminated by ethanol without destroying mesoporous structure of HMS, and the optimal calcination temperature was 550℃We also have investigated the role of mesitylene as an auxiliary structure-directing agent in the system. We studied the impacts on reaction temperature, reaction time, EtOH/H2O(mole ratio) and TMB/ODA(mole ratio) to the pore size, the orthogonal experiment result showed the importance order of influence factors is: reaction temperature> reaction time> TMB/ODA(mole ratio)>EtOH/H2O(mole ratio). When the TEOS:ODA:EtOH:H2O:TMB =1:0.27:9.09:29.6:0.27(mole ratio), reaction temperature was 45℃, reaction time was 4 hours, the pore diameter reached the maximum.