Modification Of Silica Based Mesoporous Materials And Their Application On Base Catalysis And Oxidation

The mesoporous materials have been paid much attention since the discovery of M41S series. They have large surface area and wide range of pore dimensions (2-50nm) that in sure easy accessibility of the reactants to active sites, more important, it provides a unique inorganic support that can anchor the active sites on the inorganic oxides which make them have much potential applications. In this thesis, organic functional groups were successfully anchored on the surface of MCM-41 and SBA-15, the functionalized materials kept the mesopore ordering. In addition, the catalytic activity was investigated in base-catalyzed reaction and sulfide oxidation.1. An efficient, environmentally friendly procedure is developed for the condensation of aldehydes/ketones and activated methylene compounds by using an aminopropyl-functionalized MCM-41 catalyst in aqueous solution. Different aldehydes/ketones and activated methylene compounds gave the corresponding alkenes in 78-97% isolated yields in mild reaction conditions. In comparison with organic solution, the aqueous solution gives higher yields in same reaction conditions. Further more, the aminopropyl-functionalized MCM-41 in aqueous system can be reused for 8 times without significant decrease of activity.2. Quaternary organic ammonium hydroxide functionalized SBA-15 was successfully prepared by grafting and co-condensation. XRD, BET and TEM showed that the organic-modified SBA-15 remains have one-dimensional hexagonal pore structure and large surface area. The functionalized SBA-15 was a good base catalyst in Knoevenagel condensation, the functionalized SBA-15 prepared by grafting show higher catalytic performance than the material prepared by co-condensation in the same reaction condition. Solvent has much effect on the yield. At the same reaction condition, hydroxylic solvent gives higher yield.3. Functionalized SBA-15 have been synthesized by anchoring N-propyl-benzylamine, N-propyl-o-hydroxybenzylamine, N-propyl-4-hydroxybenzylamine on the surface of SBA-15. XRD, nitrogen adsorption and desorption, FT-IR show that three group were successfully anchored on the surface of SBA-15 and the mesopore ordering decreased after the anchoring. The result materials showed good activity to Knoevenagel condensation, benzaldehyde and ethyl cyanoacetate gave the corresponding alkenes in 80% isolated yields in ethanol at 50°C for 6h. Solvent has much effect on the yield, hydroxylic solvent gives higher yield in the same reaction condition.4. Vanadyl Schiff base complexes covalently attached on the surface of MCM-41 have been synthesized by anchoring Schiff base and subsequent reaction with VO(acac)₂. XRD, nitrogen adsorption and desorption, UV-visible spectrocopy and FT-IR show that Vanadyl Schiff base complexes were successfully anchored on the surface of MCM-41 and the mesopore ordering decreased after the anchoring. The so-prepared heterogenous catalysts have showed high activity for sulfide oxidation.