Yan Di

Synthesis, characterization, and catalytic properties of stable mesoporous aluminosilicates assembled from preformed zeolite L precursors

Ordered mesoporous aluminosilicates designated as MAS-3 and MAS-8 with hexagonal mesopores have been hydrothermally synthesized from preformed zeolite L precursors under alkaline and strongly acidic conditions, respectively. MAS-3 and MAS-8 show good thermal and hydrothermal stability. Catalytic results in cracking cumene show that these mesoporous aluminosilicates are more active than conventional mesoporous aluminosilicates (Al-MCM-41). Characterization of infrared, N2 adsorption isotherms, and temperature-programmed-desorption of ammonia (NH3-TPD) have also been used to investigate these materials and the results indicate that the walls of MAS-3 and MAS-8 contain the primary and secondary structural building units, which might be responsible for the high hydrothermal stability and good activities in catalysis.

Silica nanobottles templated from functional polymer spheres

Nanosized hollow silica spheres with holes in the wall (denoted as silica nanobottles) have been successfully prepared by assembly of functional polymer nanospheres with tetraethoxysilane (TEOS) through hydrothermal methods, coupled with removal of the core by programmed calcination. The functional polymer nanospheres were obtained by emulsifier-free emulsion copolymerization of styrene and (ar-vinylbenzyl) trimethylammoium chloride. The silica nanobottle sample was characterized by thermogravimetric analysis (TG), differential thermal analysis (DTA), transmission electron microscopy (TEM), and nitrogen adsorption techniques. The above characterizations confirm that the silica nanobottles have holes of about 8 nm in the wall and this unique structural feature might be useful for their encapsulation. Furthermore, characterization by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and UV-visible absorption (UV-vis) showed that the luminescent material Eu(TTA)(3)(TPPO)(2) could be effectively encapsulated in silica nanobottles. This reveals that silica nanobottles have potential applications for nanotechniques.

Ordered mesoporous titanosilicates with catalytically stable and active four-coordinated titanium sites

The stable ordered mesoporous titanosilicate (Ti-JLU-20) has been successfully synthesized from an assembly of mixed surfactants (fluorocarbon and triblock copolymer surfactants) with preformed titanosilicate zeolite precursors at high temperature (180-220 degrees C), and catalytic tests show that Ti-JLU-20 has highly stable and active four-coordinated titanium sites in oxidations.