Narrow Results

A cooperative assembly route has been developed, by which silver nanoparticles with controlled sizes are incorporated into the channels of ordered cubic mesoporous silica (KIT-6) with different pore sizes (4.3–6.4nm). The samples were characterized by XRD, TEM, FT-IR, UV-Vis and N₂ physisorption. The pore wall of mesoporous silica can efficiently confine the growth of silver nanoparticles within the channels and their average sizes decreased with the pore size reduction of KIT-6. Catalytic activities of the resultant Ag/KIT-6-$x$ ($x$ stands for hydrothermal temperature) composite for reducing harmful organic dye Rhodamine B (Rh B) by sodium borohydride (NaBH₄) were investigated. All the Ag/KIT-6 composite samples show great catalytic activities, among which Ag/KIT-6-80 with higher loading and smaller size of Ag nanoparticles exhibits higher catalytic activity than those of Ag/KIT-6-60 and Ag/KIT-6-100.

Highly ordered mesoporous iron oxide (α-Fe₂O₃) material has been successfully obtained from mesoporous silica template, KIT-6 (3-D Cubic Ia3d symmetry), through nano-replication method. The mesoporous α-Fe₂O₃ material thus obtained exhibits well-defined mesopores (2.7 nm in diameter), high surface area (148 m²/g), high pore volume (0.47 cm³/g) and crystalline frameworks. The morphology of the mesoporous α-Fe₂O₃ material is very uniform in spherical shape of which the average particle size is about 100 nm in diameter.

A series of Ce-incorporated structure of cubic large mesoporous molecular sieves, KIT-6, with different Ce contents were synthesized by a direct hydrothermal process. A sample of Ce-loaded KIT-6 material was synthesised by incipent wetness impregnation. Similarly, catalysts with 15 wt.% Co loading on the above supports were also synthesized by incipient wetness impregnation. The supports and catalysts were characterized by X-ray diffraction, diffuse reflectance UV-vis, solid-state ²⁹Si magic-angle spinning nuclear magnetic resonance, H₂-temperature programmed reduction, H₂-temperature programmed desorption and oxygen titration. The structure of the KIT-6 support was well retained after Ce incorporation. Small amounts of Ce in the Co catalyst were found to improve the activity and increase the selectivity to C₅₊ hydrocarbons for Fischer–Tropsch synthesis, while larger amounts of Ce had the reverse effect. Meanwhile, methane selectivity shows an opposite trend as compared with that of C₅₊ selectivity. Ce-loaded KIT-6 supported Co catalyst showed lower activity than KIT-6 supported Co catalyst.