Synthesis, characterization and catalytic testing of a 3-D mesoporous titanosilica, Ti-TUD-1

An active and stable mesoporous titanosilica, denoted as Ti-TUD-1, has been synthesized using a cheap, small and multifunctional chemical, triethanolamine (TEA), instead of surfactants. TEA not only is applied as a mesopore template and as a director of positioning Ti-sites onto the internal mesopore surface via the formation of titanium-TEA complexes, but also stabilizes titanium sources, which ensures the possibility of forming isolated tetrahedrally coordinated Ti-sites. Ti-TUD-1 features three-dimensionally randomly connected mesopores with walls of about 2.5-4 nm in thickness. Its surface area can reach about 700-1000 m(2)/g and its pore sizes are tunable. After calcination at 1000 degreesC and boiling in water, it kept a high integrity, a high surface area and only a slight change in pore sizes occurred. UV-VIS spectra revealed that tetrahedrally co-ordinated Ti-sites are quite stable under thermal and hydrothermal treatments. It also showed about 5.6 times higher activity for cyclohexene epoxidation than the framework-substituted Ti-MCM-41 and similar activity compared to Ti-grafted MCM-41. (C) 2001 Elsevier Science B.V. All rights reserved.