| Ordered mesoporous materials have attracted the interest of materials scientists for its great important scientific value and potential applications in fields of catalysis, optics, adsorption, chromatogram, sensors and biology etc. However, functional groups often need to be incorporated into the mesopores in practical applications. Mesoporous materials with organic groups combine the properties of organic and inorganic modules into a single material. It does not only show the thermal stability and mechanical strength of inorganic modules, but also exhibit the variety of organic functions. By far, lots of organic functions have been incorporated into the mesopores via grafting, co-condensation, periodic mesoporous silicas or other methods.As an important kind of organic compounds, cyclopentadiene can undergo the Diels-Alder reaction with dienophiles. It can also complex with metal ions to form metallocenes which have catalytic activity in olefin polymerizations. Therefore, the incorporation of cyclopentadiene in mesoporous materials has great meanings in theoretical research and important value in practical applications. In this thesis, cyclopentadiene was introduced in SBA-15 to form cyclopentadienyl modified SBA-15 (SBA-15-Cp) which was derivatized to other organic groups modified SBA-15 based on the reactivity of cyclopentadiene. Finally, the derivatized materials were used as catalysts in organic reactions.There are three major sections in this thesis. In the first part, organosilica precursor [2-(cyclopental,3-dienyl)ethyl] triethoxysilane (TEECp) as well as SBA-15-Cp was prepared. While in the second part, neighboring dicarboxylic acids (SBA-15-(COOH)2) and spaced-amine(SBA-15-NH2) modified SBA-15 were prepared by Diels-Alder reactions of cyclopentadiene on the surface of SBA-15-Cp. On the basis of SBA-15-(COOH)2 and SBA-15-NH2, trivalent cobalt complex (SBA-15-Co(Ⅲ)) and Mn/Schiff base (SBA-15-Mn(SB)) modified SBA-15 were synthesized by in-situ reactions. In the last part, SBA-15-NH2 was used in catalyzing the Knoevenagel condensation between malononitrile and benzaldehyde, and SBA-15-Co(Ⅲ) was used in the expoxidation of cyclohexene.The first part corresponds to chapter 2 and chapter 3. Chapter 2 introduced the preparation of TEECp in detail. Schlenk techniques were involved in all the operations. In the presence of benzoyl peroxide, ethenyl tricholorosilane (CH2CHSiCl3) underwent anti-markovnikov addition with dry HBr gas to form (2-bromoethyl) tricholorosilane (BrCH2CH2SiCl3). Then BrCH2CH2SiCl3 was transformed into (2-bromoethyl) triethoxysilane [BrCH2CH2Si(OEt)3] via alcoholysis in ethanol. TEECp was obtained by the reaction of cyclopentadienyl sodium with BrCH2CH2Si(OEt)3 finally. The total yield of TEECp was about 53%. The product was characterized by NMR and FT-IR. Chapter 3 introduced the synthesis of SBA-15-Cp (n) in which n was the molar percentage of TEECp in the starting reactants. SBA-15-Cp (n) was prepared by using P123 as template and the prehydrolysis of TEOS and TEECp. The obtained materials were characterized using FT-IR, XRD, TEM and N2-asorption etc. The characterization results showed that cyclopetadiene had been incorporated in SBA-15 and many of the materials had 2D hexagonal structure. Furthermore, it also showed that the ordering of SBA-15-Cp (n) decreased increasingly with the increase of cyclopentadiene loadings. When the loadings of cyclopentadiene reached to 25%, SBA-15-Cp (n) became disorder.The second part is the core of this thesis. It includes the whole parts of chapter 4 and 7 as well as catalyst preparation parts of chapter 5 and 6. In chapter 4, SBA-15-(COOH)2 was prepared by the Diels-Alder reaction between SBA-15-Cp and maleic anhydride. And this is the first time for Diels-Alder reaction used in the functionalization of mesoporous materials. The results of FT-IR, XRD, TEM and N2-sorption etc confirmed that carboxylic acids were successfully introduced in SBA-15 after these reactions and SBA-15-(COOH)2 had 2D hexagonal symmetry. The results also showed that the pore size, specific area and pore volume of SBA-15-(COOH)2 were smaller than those of SBA-15-Cp. The acid content and dissociation constant pKa of SBA-15-(COOH)2 were 0.56 mmol/g and 4.84, respectively. Chapter 5 introduced the preparation of SBA-15-NH2 which was synthesized via the Diels-Alder reaction of SBA-15-Cp and fumaronitrile followed by reduction of cyano group using NaBH4/I2 as reductant. FT-IR, XRD, TEM and N2-asorption results showed spaced-amino groups were introduced in SBA-15 through above-mentioned reactions. Although the pore size, specific area and pore volume of SBA-15-NH2 were decreased when compared to those of SBA-15-Cp, SBA-15-NH2 still had 2D hexagonal symmetry. The NH2 loading on SBA-15-NH2 deduced from thermogravimetry was 0.95 mmol/g approximately, which was almost equal to the highest value reported in the literature. In chapter 6, trivalent cobalt modified SBA-15 (SBA-15-Co(Ⅲ)) was prepared by in-situ synthesis on the basis of SBA-15-(COOH)2. Element analysis, XPS, FT-IR, TEM and XRD results showed that trivalent cobalt was successfully introduced in SBA-15 and the content of trivalent cobalt was 0.144 mmol/g. SBA-15-Co(Ⅲ) presented 2D hexagonal symmetry. As described in Chapter 7, Mn/schiff base complex functionalized SBA-15 was prepared by reacting diacetylmanganese with schiff base modified SBA-15 (SBA-15-SB) which was synthesized by reacting spaced-amine modified SBA-15 with salicylaldehyde. FT-IR confirms that Mn/schiff base complex has been incorporated in SBA-15 after above mentioned reactions. The characterization results of XRD and TEM shows that SBA-15-Mn(SB) had a 2-dimensional hexagonal pore structure like that of SBA-15-NH2. Part 3 corresponds to the catalytic test parts of chapter 5 and chapter 6. In chapter 5, the catalytic activities of SBA-15-Cp, SBA-15-CN and SBA-15-NH2 were investigated by using Knoevenagel condensation of malononitrile and benzaldehyde as probe reaction. The results showed that SBA-15-NH2 had much higher catalytic activity and selectivity to main product than SBA-15-Cp and SBA-15-CN. This confirmed the successful incorporation of spaced-amine in SBA-15 after Diels-Alder and reduction reactions on the other hand. In chapter 6, the epoxidation of cyclohexene was used as a probe reaction to investigate the catalytic performance of trivalent complex (Ⅰ) [Co4(μ-O)4(μ-O2CH2CH3)4(py)4] and SBA-15-Co(Ⅲ). The catalytic results showed that both trivalent complex (Ⅰ) and SBA-15-Co(Ⅲ) had similar catalytic activity and selectivity to epoxide. It also showed that the activity of SBA-15-Co(Ⅲ) and selectivity to epoxide decreased with the increase of oxygen flow rate. After 6 runs, the activity of SBA-15-Co(Ⅲ) remained well. |
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