Mesoporous Zirconium Silicate Catalysts Prepared by Non-hydrolytic Acetamide Elimination
| Autoři | |
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| Rok publikování | 2015 |
| Druh | Konferenční abstrakty |
| Fakulta / Pracoviště MU | |
| Citace | |
| Popis | Non-hydrolytic sol-gel reactions are efficient alternatives to classical aqueous techniques for synthesis of multimetallic oxides and inorganic-organic hybrid materials. This process provides better reaction control and higher homogeneity of prepared materials. We developed non-hydrolytic sol-gel routes to several groups of metallosilicate materials and efficient catalysts based on acetamide elimination reactions (1,2). Our approach is based on the acetamide condensation reaction of silicon tetraacetate Si(OAc)4 and zirconium diethylamide Zr(NEt2)4 that leads to the formation of Si–O–Zr bonds in the xerogel framework (IR, 29Si CPMAS NMR). Diethylacetamide and acetanhydride were confirmed (GC-MS, 1H NMR) as the reaction byproducts. To achieve the mesoporous nature of the xerogels, the reaction was successfully modified by the addition of the Pluronic P123 template with structure-directing and protecting functions which allow to prepare stiff gels. After heat treatment the template is burned out and xerogels are mesoporous with high surface areas. The presence of four-coordinated Zr atom introduces catalytic activity to our products. Calcined Si/Zr xerogels were tested in two types of catalytic reactions and the product yields were analyzed by GC-MS and 1H NMR. In the case of MPV reduction of 4-tert-butylcyclohexanone in 2-propanol the catalytic yield of 4-tert-butylcyclohexanone reached up to 55 % with a high selectivity for the trans product. Our Si/Zr xerogels are also very effective catalysts for aminolysis of styrene oxide with the 94 % conversion to catalytic products. The resulting xerogels and volatile byproducts were characterized by liquid and solid-state NMR, IR, GC-MS, surface area analysis, TGA, XRD and DRUV-Vis. |
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