Abstract:

With a gel of relatively low template content and high n(Ti)/n(Si) ratio up to 1/4, mesoporous titanosilicate has been synthesized under static conditions by hydrothermal crystallization and post-treatment. The novel approach includes a separate hydrolysis procedure before mixing the titanium and silicon resources during gel preparation. By means of XRD, FT-IR, UV-Vis DRS and selective catalytic oxidation, it reveals that the new approach effectively prevents titanium ions from formation of indissoluble titaniosilicate species in the synthesis gel at high titanium content. The obtained material possesses a highly ordered, hexagonal MCM-41 structure and is thermally stable and catalytically reactive in selective catalytic oxidation. The addition of tetrabutylammonium hydroxide during gel preparation not only helps the formation of stable soluble titanium species hence to improve the efficiency of titanium, but also results in the framework of the material more cross-linked and ordered.

Key words: Mesoporous titanosilicate, Hydrothermal crystallization, Hydrothermal post-tneatmenl, MCM-41 structure, Characterization