Synthesis And Characterization Of MSU-type Mesoporous Molecular Sieves

This thesis emphasized on the preparation of mesoporous molecular sieves MSU. And the influence of synthetic factors on the structure and properties of silica MSU are investigated by the techniques of X-Ray diffraction (XRD), IR spectra ,thermo gravimetric (TG), Scanning Electron Microscope (SEM) and N2 adsorption-desorption isotherms .On the basis of above results, the synthesis of MSU materials modified in framework by Al and B are studied. Besides these ,we also investigated the stability of MSU and Al-MSU.Through the routine of sol-gel, silica MSU materials ,which has high degree of crystallization, has been prepared. Respectively, sufactant and source of silicate is polyoxyethylene (10) stearyl ether (C18EO10),tetraethyl orthosilicate (TEOS). The composition of gel is 1TEOS:0.225C18EO10:150H2O. The PH of gel, the crystallizing-temperature and the crystallizing-time have certain effects on the structure of mesoporous molecular sieves.It is found that with sodium silicate as organic source ,both in basic and in acidic conditions, MSU-type mesoporous silica can be obtained. The structural and textural properties of materials are dependent on the synthesis condition. When the value of PH equals to 6, MSU with high degree of crystallization has been made. It is probably corresponds to the condensation of silica precursors.Compared the formal with the latter , its X-Ray diffraction line is sharper ,which may contribute to the amount of -SiOH. When calcined ,the condensation of -SiOH will make the framework condense. A fixed amount of silicate can only use a fixed amount of surfactant.A mesoporous molecular sieves silica prepared with sodium silicate solution as silica source, is shown on the basis of XRD measurements to be substantially more stable to calcinations at 900℃ for 2 brand to steam treatment at 760℃ for7hr.It has been shown that the incorporation of Al can significantly increase the valueof a0 and the temperature of the removal of surfactant. The degree of crystallization of Al-MSU decreased with the increasing of Al content in the wall. In this study, we still obtained the good-crystallized mesoporous molecular sieve when the Si/Al has achieved 25 .we find that Al-MSU is less stable ,which is probably corresponds to the structure and configuration.