Transition metal nanoparticles protected by amphiphilic block copolymers as tailored catalyst systems
Transition metal nanoparticles protected by amphiphilic block copolymers as tailored catalyst systems
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DOI：
10.1007/s003960050090
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发表时间：
1997-04
影响因子：
2.4
通讯作者：
A. Mayer;J. E. Mark
中科院分区：
文献类型：
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作者：
A. Mayer;J. E. Mark
在保护性两亲嵌段共聚物的存在下，通过还原相应的金属前驱体制备了几种稳定的钯、铂、银和金胶体。采用具有不同疏水性的钯和铂前驱体，即氯化钯PdCl2、醋酸钯Pd(CH3COO)2、六氯铂酸H2PtCl6和乙酰丙酮铂(CH3COCH=C(O-)CH3)2，考察了它们催化活性的差异。研究了它们稳定这种过渡金属胶体的能力的聚合物是聚苯乙烯-b-聚氧乙烷和聚苯乙烯-b-聚甲基丙烯酸。用透射电子显微镜测定了金属颗粒的大小和形貌，发现金属颗粒在纳米范围内。以环己烯加氢反应为模型反应，考察了钯、铂胶体的催化活性。保护的钯和铂纳米粒子具有催化活性，最终转化率可达100%环己烷。根据聚合物嵌段类型和长度、前驱体类型和还原方法的选择，可以获得不同的纳米颗粒形貌和催化活性。因此，这些新颖的催化活性金属-聚合物体系是开发定制催化剂体系的很有前途的候选者。
Several stable palladium, platinum, silver, and gold colloids were prepared by reducing the corresponding metal precursors in the presence of protective amphiphilic block copolymers. Some palladium and platinum precursors with different hydrophobicities, namely palladium chloride PdCl2, palladium acetate Pd(CH3COO)2, hexachloroplatinic acid H2PtCl6, and platinum acetylacetonate Pt(CH3COCH = C(O-)CH3)2, have been used in order to investigate differences in their catalytic activity. The polymers investigated for their ability to stabilize such transition metal colloids were polystyrene-b-poly(ethylene oxide) and polystyrene-b-poly (methacrylic acid). The metal particle sizes and morphologies were determined by transmission electron microscopy and found to be in the nanometer range. The catalytic activity of the palladium and platinum colloids was tested by the hydrogenation of cyclohexene as a model reaction. The protected palladium and platinum nanoparticles were found to be catalytically active, and final conversions up to 100% cyclohexane could be obtained. Depending on the choice of polymer block types and lengths, the precursor type, and the reduction method, different nanoparticle morphologies and catalytic activities could be obtained. These novel catalytically active metal-polymer systems are thus promising candidates for the development of tailored catalyst systems.