Characterization of Lewis acidity of cation-exchanged montmorillonite K-10 clay as effective heterogeneous catalyst for acetylation of alcohol
Characterization of Lewis acidity of cation-exchanged montmorillonite K-10 clay as effective heterogeneous catalyst for acetylation of alcohol
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DOI：
10.1016/j.molcata.2008.01.013
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发表时间：
2008-04-02
影响因子：
--
通讯作者：
Satsuma, Atsushi
中科院分区：
文献类型：
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作者：
Shimizu, Ken-Ichi;Higuchi, Tomoya;Satsuma, Atsushi
本文研究了14种金属离子交换蒙脱石K-10粘土（Mn ~+-mont）在室温下对环己醇与乙酸酐的乙酰化反应的催化活性。活性随交换阳离子荷径比的增加而增加。其中Fe ~（3+）-mont催化剂的活性最高，高于其它Fe ~（3+）催化剂FeCl_3中心点6 H（2）O和FeCl_3/SiO_2，常规酸催化剂Al_2 O_3和HZSM_5，以及均相刘易斯酸Sc（OTf）（3）。Fe 3 +-mont表现出高周转数（TON = 49，500），并且可以回收而不损失活性。以吡啶、乙腈和丙酮为探针分子，用红外光谱表征了Fe 3 +-mont、Yb 3 +-mont和FeCl 3/SiO2的酸性。丙酮吸附量热分析表明，催化剂主要以刘易斯酸形式存在，其刘易斯酸强度的大小顺序为：Fe 3 +-mont > Yb 3 +-mont > FeCl 3/SiO2。从催化活性与酸性的关系出发，讨论了影响催化剂乙酰化活性的因素。(C)2008 Elsevier B. V.保留所有权利。
Catalytic activity of 14 types of metal ion-exchanged montmorillonite K-10 clay (Mn+-mont) is tested for the acetylation of cyclohexanol with acetic anhydride at room temperature. The activity increases with an increase in the charge/radius ratio of exchanged cation. The activity of Fe3+-mont is the highest and is higher than those of other Fe3+ catalysts, FeCl3 center dot 6H(2)O and FeCl3/SiO2, conventional acid catalysts, Al2O3 and HZSM5, and homogeneous Lewis acid, Sc(OTf)(3). Fe3+-mont exhibits a high turnover numbers (TON = 49,500) and can be recycled without a loss in activity. Acidity of Fe3+-mont, Yb3+-mont and FeCl3/SiO2 was characterized by IR spectroscopy using three probe molecules: pyridine, acetonitrile and acetone. These catalysts dominantly act as Lewis acid, and the Lewis acid strength changes in the order of Fe3+-mont > Yb3+-mont > FeCl3/SiO2, as suggested by acetone adsorption microcalorimety. From the relationship between the activity and the acidic character, factors affecting the catalytic activity for the acetylation are discussed. (C) 2008 Elsevier B.V. All rights reserved.