Synthesis And Application Of Ordered Mesoporous Ti-containing Nanocomposites

The synthesis and assembly of mesostructured materials represent a hotspot direction in the research fields of materials science, chemistry, physics and life science. Recently, along with of the deepening of synthesis of ordered mesoporous materials by organic-inorganic self-assembly, which makes synthesis and applications of the ordered mesoporous composites has become a new hotspot. As conventional photocatalyst titanium dioxide has many of shortcomings, synthesis and application of Ti-containing ordered mesoporous nanocomposites have aroused widespread attention. In addition, powder catalyst has a large weight loss in use process, and not conducive to the recycled use. Shaping is of great significance for industrial catalysts.The thesis is composed of three chapters. The first chapter is a detailed review on the development and research status of mesoporous materials and titanium dioxide photocatalyst.In chapter 2, we report a novel synthesis for easily shaped Ti-containing mesoporous silica, which includes three steps: obtaining mesostructured silicate, grafting functional moieties, and thermal treatment. The second grafting step involves as-prepared mesoporous silica SBA-15 as a host template, an inorganic titanium salt (TiCl3 or TiOSO4) as a titanium source, and water as a solvent. As-prepared mesoporous silicates share the advantages of maintenance of silanol groups for grafting and easy shaping. Removal of the organic template and formation of catalytic active centers simultaneously occur upon calcination. This procedure is time and energy saving, and therefore industrially feasible. The obtained Ti-containing mesoporous silicates have the highly ordered 2-D hexagonal mesostructure, high surface areas, large pore volumes, uniform pore sizes, and tetrahedrally incorporated titanium species in silicate frameworks. The influence of the titanium source is also discussed.Chapter 3 described highly efficient adsorption and degradation of bulky dyes in waste water has been demonstrated on ordered mesoporous C–TiO2 nanocomposites. The ordered mesoporous composites with different titanium content were synthesized via the surfactant self-assembling approach by using preformed phenolic resins as carbon sources and triblock copolymer F127 as a structure-directing agent. Orderedmesoporous nanocomposites can be obtained with large pore sizes (3.9～4.2 nm), large pore volumes (0.22～0.30 cm3/g), and high surface areas (188～348 m2/g), highly crystalline anatase. The nanocrystallites anatase is small and dispersed homogeneously at skeleton carbon pore walls which are"glued"by amorphous carbon. The titania content is as high as 22～58 wt%. Modified carbon can improve activity of titanium dioxide, increased the stability of anatase, and made the energy band of the titanium dioxide narrow. The ordered mesoporous C–TiO2 nanocomposites can use visible light photodegradation dyes, have the stable properties, and can be effectively reused. The integral material has the potential for industrial application.