Sonogashira Couplings on the Surface of Montmorillonite-Supported Pd/Cu Nanoalloys

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• 作者：Wei Xu ; Huaming Sun ; Bo Yu ; Guofang Zhang ; Weiqiang Zhang ; Ziwei Gao
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：November 26, 2014
• 年：2014
• 卷：6
• 期：22
• 页码：20261-20268
• 全文大小：516K
• ISSN：1944-8252

文摘

To explore the true identity of palladium-catalyzed Sonogashira coupling reaction, montmorillonite (MMT)-supported transition metal nanoparticles (MMT@M, M = Pd, Cu, Fe, and Ni) were prepared, characterized, and evaluated systematically. Among all MMT@M catalysts, MMT@Pd/Cu showed the highest activity, and it was successfully extended to 20 examples with 57%鈥?7% yields. The morphology characterization of MMT@Pd/Cu revealed that the crystalline bimetallic particles were dispersed on a MMT layer as nanoalloy with diameters ranged from 10 to 11 nm. In situ IR analysis using CO as molecular probe and XPS characterization found that the surface of Pd/Cu particles consisted of both catalytic active sites of Pd(0) and Cu(I). The experiments on the catalytic activities of MMT@M found that Pd/Cu catalyst system exhibited high activity only in nanoalloy form. Therefore, the Pd/Cu nanoalloy was identified as catalyst, on which the interatom Pd/Cu transmetalation between surfaces was proposed to be responsible for its synergistic activity.

Keywords:

bimetallic catalysis; nanoalloy; montmorillonite; Sonogashira coupling; CO absorption