| Summary: | 碩士 === 東海大學 === 化學系 === 96 === Periodically ordered mesoporous magnesium oxide (H-MgO) was synthesized in a double replication procedure and was impregnated with NaOH to obtain 1 wt% Na-H-MgO. These two catalysts、 nano-MgO (N-MgO)、1 wt% Na-N-MgO and MgO were characterized with XRD, physisorption analyzer, SEM and TEM, TGA and TPD to obtain the physical properties, i.e., the structure, surface area, pore volume and pore size distribution, particle size and shape as well as the bascity. According to XRD and TEM results, H-MgO exhibited characteristic hexagonal pore structure. The BET surface area followed the order of N-MgO＞H-MgO＞1%Na-H-MgO＞C-MgO. The base amount followed the order of 1%Na-H-MgO＞1%Na-N-MgO＞H-MgO＞N-MgO＞C-MgO.
The following reactions were performed over these catalysts in a batch reactor：(1) self-condensation of n-heptylaldehyde；(2) aldol condensation of benzaldehyde with acetophenone. The effects of different catalysts, reaction temperature, stirring speed, solvent, and reaction time on catalytic results were investigated. The system was free of diffusional limitation at a stirring speed of 800 rpm. The catalytic activity decreased as follows: 1%Na-H-MgO＞1%Na-N-MgO＞H-MgO＞N-MgO＞C-MgO, that is consistent with the relative catalyst base amount. In addition, the conversion of both reactions and the 2-pentyl-2-nonenal selectivity in the reaction of n-heptaldehyde enhanced with increasing the reaction temperature and the time duration whereas the chalcone selectivity nearly remained 100 % in the reaction of benzaldehyde with acetophenone.
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