New route for synthesis of highly ordered mesoporous silica with very high titanium content

摘要

Meso-structured titanosilicates with variable amounts of titanium have been hydro-thermally synthesized under static conditions via a new route. By a separate hydrolysis procedure during gel preparation, this approach effectively prevents titanium ions from formation of indissoluble titanium species in the mixture at very high titanium content. The physicochemical properties of these materials were characterized by means of XRD, FT-IR, UV-Vis DRS and catalytic oxidation of 4-methylphenol with dilute hydroperoxide. In contrast to literature reports, this novel method can lead to mesoporous titanosilicates with a highly ordered MCM-41 hexagonal phase even in a gel with n(Ti)(Si) up to 1/4 and a relatively low template content. It reveals that these materials are chemically homogeneous. During crystallization, titanium ions were partially incorporated into the MCM-41 framework. The addition of TBAOH resulted in a more cross-linked and ordered wall structure.