Syntheses Of Novel Ti-containing Mesoporous Silicates And Their Catalytic Performance In Oxidation Of Octene

The discovery of Ti-containing molecular sieves added a new dimension to the applications of molecular sieves in catalysis. Titanium silicate, TS-1, and TS-2 with MFI and MEL structures, respectively, were shown to the active for selective oxidation of a variety of organic compounds in the presence of hydrogen peroxide. However, these applications were restricted to molecules smaller than 7 ? owing to the pore size limitation. This barrier was overcome with the introduction of mesoporous molecular sieves such as MCM-41, MCM-48 and SBA-15. Because of the wide pore size distribution and highly hydrothermal stability, titanium-containing SBA-15 seems more attractive in the application of catalytic oxidation of large organic molecules.In this thesis, we have prepared novel Ti-containing mesoporous silicates and studied their catalytic performance in oxidation of octene.The thesis is composed of five chapters. The fist chapter is a detaild review on the syntheses of Ti-containing molecular sieves and their catalytic performances.Chapter 2 introduces a novel method of syntheses of Ti-containing molecular sieves. Using mixed inorganin"acid-base pairs"(TiCl4 and tertrabutyl titanate) as the titanium sources and tetraethoxysilane as silica source and triblock copolymer as the struture-directing agent through hydrothermal methode.Characterization using XRD,Uv-vis, FT-IR,TEM and nitrogen sorption isotherm techniques reveals that the Ti-containing molecular sieves posses ordered 2-D hexagonal mesostructures,highly surface areas(986– 1349 m2/g),uniform pore sizes (4.5– 6.3 nm), large pore volumes(0.81– 1.2 cm3/g),and tetrahedrally incorporated titanium species in silica network. The Ti-containing molecular sieves show catalytic performance in the epoxidation of 1-octene using tert-butylhedroperoxide as an oxidant, the Ti(M12.5)-SBA shows the highest catalytic performance, conversion of 1-octene is 47%.The synthersis of organic functional Ti-containing molecular sieves are discussed in chapter 3 and chapter 4. In chaper 3, the organic founctional Ti-containing molecular sieves can be assemed by using a single inorganic TiCl3 as titanium source and tetraethoxysilane and 1,2-bis(triethoxysilyl)ethane as the silica soures and triblock copolymer as the struture-directing agent through hydrothermal methode. The nanocomposites have the highly ordered 2-D hexagonal mesostructure, high surface areas, large pore volumesand large pore diameters. The Uv-vis and FT-IR technique, indicate that the pore walls are composed of polymer, silica and Ti species. The highest catalytic cinversion (62%) of 1-octene in epoxidation is realized on an organic founctional Ti-containing molecular sieve(Ti(S6.7)-SBA).In chaper 4, highly ordered mesoporous bifunctional nanocomposite Ti-SiO2-Polymer have been successfully synthesized by the evaporation-induced co-assembly method, wherein soluble resol polymer is used as an organic precursor, tetraethoxysilane as silica source, and triblock copolymer as the struture-directing agent. The nanocomposites have the highly ordered 2-D hexagonal mesostructure, high surface areas, large pore volumes and large pore diameters. The XPS and FT-IR technique, indicate that the pore walls are composed of polymer, silica and Ti species. These bifunctional nanocomposite: Ti-SiO2-Polymer show remarkably catalytic avtivity in the epoxidation of 1-octene using tert-butylhedroperoxide as an oxidant,the hightest conversition of 1-octene can achive 62%.In the last chapter,we prepared the Ti-containing molecular sieves through postsynthesis. Rapid introduce the titanium into as - made SBA-15 occluded with template. These Ti-containing molecular sieves show excellent catalytic avtivity in 1-octene eopoxidation reaction, the hightest conversition of 1-octene can achive 65%.