Synthesis Of Mesoporous Materials With High Stability By Post-synthetic Treatment

The poor stability of mesoporous materials limits their applications greatly, and many works have been done to improve the (hydro)-thermal stability. In this thesis, several kinds of ordered mesoporous materials with high stability were synthesized by post-synthetic treatments. The obtained samples were characterized by a variety of techniques, such as XRD, XRF, SEM, TEM, FTIR, Solid-state MAS NMR and N2 adsorption measurement.Pure phases of MCM-22, UTM-1 and kenyaite were obtained by varying the SiO2/Al2O3 ratio in the gel system. Subsequently, a kind of hydrothermally stable mesoporous materials MS-n (n denotes the pH value, n=9, 7, 5, 3) was prepared for the first time by post-synthetic treatment of the UTM-1 zeolite at room temperature. The 823 K calcined MS-7 exhibited remarkable hydrothermal stability. After being treated in boiling water for 312 h, the sample remained still well-ordered and kept a high BET specific surface area of 922 m²/g, a high pore volume of 1.08 cm³/g as well as a mesoporous pore size of 2.2 nm. The higher condensation of the pore walls and the higher percent of 4-folded Al were suggested to be responsible for the remarkable hydrothermal stability.Ordered mesoporous materials MSK-n (n denotes the pH value, n=9, 7, 5, 3) was synthesized from kenyaite, a layered silicate with multi-layers of SiO₄ tetrahedra, by refluxing with surfactant and a subsequent pH adjustment process at room temperature. This method broke through the limitation that only the layered silicate consisted of single layers of SiO₄ tetrahedra can be used to synthesize mesoporous materials. This method also provided a possible way to prepare ordered mesoporous materials from other layered minerals with multi-layers of...