Synthesis Of Inorganic-organic Mesoporous Materials For Aerobic Oxidation Of Benzyl Alcohol

Recently, the selective oxidation of alcohols to the corresponding carbonyl compounds, which is important for medicine and industry of fine chemicals, is a subject of considerably academic interest. The traditional industrial production requires stoichiometric oxidants. However, the reaction of these oxidants will produce a large number of inorganic metal salts, and these inorganic metal salts are usually hazardous and toxic. From the viewpoints of environment, we should choose some green oxidants, such as air, O2 and H2O2 as the oxidant in place of the stoichiometric metal oxidants. Load on such a noble metal catalyst has an excellent reaction activity, but it is not widely used because of its high price.Some reviews have shown that metal organic complexes in the liquid phase oxidation have a good catalytic activity and selectivity. However, these metal organic complexes are easy to form dimeric peroxo- orμ-oxo species, and this formation of the new material leads to deactivation of the metal organic complexes. In addition, they are so easily soluble in reactant or product that they can't be recycled. In order to deal with these problems, we propose a new method that immobilizes metal organic complexes on mesoporous molecular sieve to form an organic-inorganic hybrid material. These materials not only have high intensity and stability of inorganic materials, but also have the nature of organic ligand, realizing the complementary strengths of organic and inorganic materials. There are many methods of immobilizing metal organic complexes on mesoporous molecular sieve, such as parcel method, ship-in-bottle, surface grafting, anchoring method, total hydrolysis condensation and sol-gel method. In this thesis, surface grafting and anchoring synthesis method are used for synthesis of the organic-inorganic catalysts. First, the organic groups of amino have been introduced into the fameworks of mesoporous materials (SBA-15) through co-condensation methods. Then, some organic groups,such as Copper(Ⅱ)-8-quinoliol and Copper(Ⅱ)-salicylaldehyde complexes have been successfully introduced into amino-modified SBA-15, which are Copper (Ⅱ)-8-quinoliol functionalized SBA-15 materials (named as Cu-Q-SBA-15) and Copper (Ⅱ)-salicylaldehyde functionalized SBA-15 materials (named as Cu- SYQ-SBA-15). The modified material retains its structure and metal complexes are successfully immobilized, which are verfied by XRD, N2 adsorption, SEM, FT-IR, CHN element analysis and ICP-AES analysis. Cu-Q-SBA-15 was tested as catalysts for liquid benzyl alcohol oxidation using H2O2 (4ml) as oxidant, using water as the solvent, at 80℃for 6h. It is found that benzyl alcohol conversion is 36.2%, and benzaldehyde selectivity is 85.2%. Catalysts can recycle three times without apparent deactivation. The similar reaction result was obtained over copper (Ⅱ)-salicylaldehyde functionalized SBA 15.Bis(8-quinolinol)copper(Ⅱ) and tri(8-quinolinol)iron(Ⅲ) complexes were direct anchored onto amino-modified SBA-15. XRD, N2 adsorption, SEM, FT-IR, CHN element analysis and ICP-AES analysis confirmed that the structure of these materials was retained, and metal complexes were successfully immobilized. The result shows that these materials maintained homogeneous organic metal complexes's structure and composition. We also examined the influence of time, temperature, the amount of oxidant and solvent on the oxidation of benzyl alcohol. It is shown that the heterogeneous catalysts showed better catalytic performance.