Zhiping Shan

One-step synthesis of a highly active, mesoporous, titanium-containing silica by using bifunctional templating.

A highly active, three-dimensional, mesoporous titanosilica, TiTUD-1, with comparable properties to Ti-grafted mesoporous silica MCM-41, has been prepared in a one-step synthesis. A non-surfactant chemical, triethanolamine, was used as a template molecule. Triethanolamine easily forms complexes with titanium alkoxides, yielding titanatrane complexes, which together with free triethanolamine form meso-sized aggregates that template mesopores upon increasing the temperature of the synthesis mixture. Triethanolamine served as both mesopore template and ligand for the titanium complexes, which represent the majority of the catalytic-site precursors. The formation of the silica network and the titanium insertion were followed by a combination of diffuse reflectance UV/ Vis/NIR and FTIR spectroscopy. A titanium-rich phase was obtained on the mesopore surfaces during calcination, allowing for easy accessibility of the reactants to the catalytic sites. TiTUD-1 is about six times more active than framework-substituted Ti-MCM-41 and has similar activity to Ti-grafted MCM-41.

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

Abstract 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 co-ordinated 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°C 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.

A new templating method for three-dimensional mesoporenetworks

A new templating method using small, inexpensive non-surfactant chemicals has been developed facilitating the synthesis of hydrothermally stable foam-like mesopore networks with high surface areas.

Synthesis of tailored bimodal mesoporous materials with independent control of the dual pore size distribution

A new synthesis method is presented to prepare multi-structured porous materials through a fully chemical route that allows control of the smaller and larger mesopore sizes independently.