Well-defined group IV supported catalysts: An efficient way to increase activities in the deperoxidation of cyclohexyl hydroperoxide with environmentally systems
Well-defined group IV supported catalysts: An efficient way to increase activities in the deperoxidation of cyclohexyl hydroperoxide with environmentally systems
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DOI：
10.1016/j.apcata.2005.05.017
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发表时间：
2005-08
影响因子：
5.5
通讯作者：
†. R. P. Saint-Arroman;J. Basset;F. Lefebvre;B. Didillon
中科院分区：
文献类型：
--
作者：
†. R. P. Saint-Arroman;J. Basset;F. Lefebvre;B. Didillon
通过构建活性中心的分子工程方法，合成了组成均匀、分布均匀的SiO_2负载(SiO)_3MoR(M=Ti，Zr，Hf；R=H，Tbu)金属有机配合物。采用固体核磁共振、红外光谱、显微分析等方法对催化剂进行了表征。为了开发环境友好的工艺，这些固体被用作环己基氢过氧化氢脱氧的催化剂，这是合成尼龙6-6的前体己二酸的重要步骤。最好的金属是钛，其性能远远超过先前在专利文献中报道的焙烧负载钛催化剂。研究了配位球的性质，特别是钛与二氧化硅载体之间的共价键数目对催化活性的影响。各种实验表明，该催化剂主要为多相催化。在反应的第一阶段，有大量的钛被浸出，但在一些循环后，反应速度保持不变，这表明该催化剂应该是环己基氢过氧化氢多相去过氧化的良好候选者。
Silica-supported (SiO)3MOR (M=Ti, Zr, Hf; R=H,tBu) organometallic complexes of group 4, uniform in composition and in distribution, were synthesized via a molecular engineering approach of the construction of active sites. These catalysts were fully characterized by various methods including solid-state NMR, infrared spectroscopy and microanalysis. In the goal to develop environmentally friendly processes,these solids were used as catalysts for the deperoxidation of cyclohexyl hydroperoxide, an important step in the synthesis of adipic acid, a precursor of nylon 6-6. The best metal is titanium and its performances are far above those of calcined supported titanium catalysts previously reported in the patent litterature. The influence on the catalytic activity of the nature of the coordination sphere and more specifically the number of covalent bonds between titanium and the silica support were studied. The catalysis is mainly heterogeneous as shown by various experiments. A non-negligible amount of titanium is leached during the first stages of the reaction but after some recycles the reaction rate remains constant allowing to suggest that this catalyst should be a good candidate for heterogeneous deperoxidation of cyclohexyl hydroperoxide.