Ordered Mesoporous Mixed Metal Oxides: Remarkable Effect of Pore Size on Catalytic Activity
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- 作者：Madhavi N. Pahalagedara ; Lakshitha R. Pahalagedara ; Chung-Hao Kuo ; Saminda Dharmarathna ; Steven L. Suib
- 刊名：Langmuir
- 出版年：2014
- 出版时间：July 15, 2014
- 年：2014
- 卷：30
- 期：27
- 页码：8228-8237
- 全文大小：513K
- ISSN：1520-5827
文摘
We report the synthesis of ordered mesoporous NiAl mixed metal oxides (MMOs) from NiAl-layered double hydroxides (LDHs) through a soft template method using pluronic-F127 as the structure-directing agent. Ordered mesopores were obtained by the thermal decomposition of as-synthesized LDHs at different temperatures. The effects of the pluronic-F127 amount and the calcination temperature on the pore size distribution of the MMO were investigated. NiAl MMOs exhibited excellent catalytic activity in the Knoevenagel condensation of benzaldehyde with acidic methylene group-containing malononitrile. Finally, the dependence of the catalytic activity on the surface properties of NiAl MMOs was investigated. The pore diameter and the pore volume of NiAl MMOs were well correlated with the performance of the catalysts. MMO obtained from the calcination of NiAl-F1273%LDH at 750 掳C for 5 h gave the highest conversion (>99%) in the Knoevenagel condensation in 30 min. The optimum pore diameter for the model reaction described here was 7.7 nm, which gave rise to more than 99% conversion with 100% selectivity. Ethanol gave the best conversion at 60 掳C. The regenerated catalyst showed 93.0 and 89.0% of the initial catalytic activity after the first and the second regeneration cycles, respectively.