Conditions of Formation of Copper Phyllosilicates in Silica-Supported Copper Catalysts Prepared by Selective Adsorption
Conditions of Formation of Copper Phyllosilicates in Silica-Supported Copper Catalysts Prepared by Selective Adsorption
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DOI：
10.1021/jp013153x
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发表时间：
2002-02
影响因子：
3.3
通讯作者：
T. Toupance;M. Kermarec;A. J. Lambert;C. Louis
中科院分区：
文献类型：
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作者：
T. Toupance;M. Kermarec;A. J. Lambert;C. Louis
研究表明，在通过四氨合铜络合物[Cu(NH₃)₄(H₂O)₂]²⁺在二氧化硅上的选择性吸附制备Cu/SiO₂样品的过程中，形成了两种负载型Cu²⁺物种：接枝的Cu²⁺离子和层状硅酸铜。接枝的Cu²⁺离子的形成是由于溶液中高pH值导致二氧化硅颗粒表面带负电，从而使Cu²⁺氨络合阳离子在溶液中发生静电吸附。Cu²⁺离子的接枝发生在随后的干燥步骤中。层状硅酸铜在溶液中形成，它是由二氧化硅溶解产生的硅酸与溶液中的[Cu(OH)₂(H₂O)₄]⁰络合物之间的反应导致的。这两种Cu²⁺物种在还原后都会形成小的金属颗粒。本文研究了几个制备参数：金属前驱体浓度、前驱体溶液的pH值、溶液与二氧化硅的接触时间以及向前驱体溶液中添加硝酸铵。层状硅酸铜的量取决于……
It is shown that, during the preparation of Cu/SiO2 samples by selective adsorption of copper tetraammine complex [Cu(NH3)4(H2O)2]2+ on silica, two types of supported CuII species form: grafted CuII ions and copper phyllosilicate. The formation of grafted CuII ions results from electrostatic adsorption of CuII ammine complex cations in solution onto the surface of silica particles negatively charged due to the high solution pH. Grafting of CuII ions occurs during the subsequent drying step. The formation of copper phyllosilicate takes place in solution. It results from a reaction between silicic acid arising from silica dissolution and [Cu(OH)2(H2O)4]0 complex in solution. Both CuII species lead to small metal particles after reduction. Several preparation parameters were investigated in this paper: the metal precursor concentration, the pH of the precursor solution, the solution/silica contact time, and the addition of ammonium nitrate to the precursor solution. The amount of copper phyllosilicate depe...