Metal–supported catalysts encapsulated in mesoporous solids: Challenges and opportunities of a model concept-猫眼课题宝

DOI：

10.1002/pssb.201248454

发表时间：

2013-06

期刊：

physica status solidi (b)

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

W. Grünert;H. Gies;M. Muhler;S. Polarz;C. Lehmann;Dennis Großmann;M. V. D. van den Berg;O. Tkachenko;A. De Toni;I. Sinev;M. Bandyopadhyay;Vaishali V. Narkhede;A. Dreier;K. Klementiev;A. Birkner;E. Löffler

概述了旨在研究多相催化剂中金属-载体相互作用的模型系统的工作。在这些模型中，金属和载体都通过作为客体引入介孔主体而被小型化。这种模型的使用通过包裹在 MCM-48 中的 AuTiO2 团簇和包裹在硅质中孔系统和碳纳米管中的 CuZnO 团簇进行了证明。这些模型有望提供更好的机会来跟踪催化剂活化和催化过程中载体成分的变化，包括最初可能被捕获在载体表面上的毒物的作用。需要满足的挑战是合成和催化过程中介孔基质的稳定性、基质表面对任何催化剂组分可能的反应性，以及后者与基质的聚集和分离。所遇到的挑战包括在Au-TiO2/MCM-48催化剂制备过程中的孔损伤、在从水介质中沉积锌物质过程中硅质壁与锌离子的失活相互作用以及在煅烧和还原过程中Cu组分的聚集。研究得出的结论是，Au-TiO2 界面的有序性（以及金中的外延和晶体应变）与 Au/TiO2 催化剂在 CO 氧化中的高活性无关。在Cu-ZnO甲醇合成催化剂模型中，可以观察到两种不同类型的Cu-Zn相互作用：强还原条件下Zn2+和Cu(0)之间的直接接触，以及合金纳米颗粒（纳米黄铜）的形成。讨论了这些相互作用与甲醇合成反应的相关性。

An overview of work with model systems designed to study metal–support interactions in heterogeneous catalysts is given. In these models, metal and support are both miniaturized by introduction as guests into a mesoporous host. The use of such models is demonstrated with AuTiO2 clusters encaged in MCM‐48, and CuZnO clusters encapsulated in siliceous mesopore systems and in carbon nanotubes. The models promise a better opportunity to track changes in the support component during catalyst activation and catalysis, including the action of poisons that may at first be trapped on the support surface. Challenges to be met are the stabilization of the mesoporous matrix during synthesis and catalysis, possible reactivity of the matrix surface towards any of the catalyst components, as well as clustering and segregation of the latter from the matrix. The challenges were encountered as pore damage during preparation of AuTiO2/MCM‐48 catalysts, as deactivating interactions of siliceous walls with zinc ions during deposition of zinc species from aqueous media, and as clustering of the Cu component during calcination and reduction. Among the conclusions drawn from the studies are the irrelevance of order at the AuTiO2 interface (and, hence, of epitaxy and of crystal strain in gold) for high activity of Au/TiO2 catalysts in CO oxidation. In the models for CuZnO methanol synthesis catalysts, two different types of CuZn interaction could be observed: a direct contact between Zn2+ and Cu(0) under strong reducing conditions, and the formation of alloy nanoparticles (nano‐brass). A discussion of the relevance of these interactions for the methanol synthesis reaction is given.

Metal–supported catalysts encapsulated in mesoporous solids: Challenges and opportunities of a model concept

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