Subject of Contribution

In catalysts type I the metal ion - metal nanocluster ensemble sites are formed at the perimeter of nanoparticles stabilized on reducible oxide supports. Typical representatives of this type of catalysts are Pt/SnOa or Ru-Sn/AlaOs and Pt/Ti02 catalysts. 

In catalyst type II the above sites are created and stabilized at the surface of the first metal. The stabilization of highly active metal ions at the atomic closeness of metal nano-cluster can be achieved by one of the following methods  

The metal ion - metal nanocluster ensemble sites can contain either one or two metal components. In different forms of copper and gold catalysts, the metal can exist in both forms, i.e., as metal ion and the metal nanocluster. These systems will be considered as a mono-element metal ion - metal nanocluster ensemble sites. However, as it will be demonstrated later, systems containing two elements are more common. In most of these systems the metal ions are formed from elements of well known red-ox metals, such as tin, rhenium, iron, tungsten, molybdenum, etc. while the metal nanoparticles are noble metals, such as platinum, ruthenium, etc. 

In this work we shall focus on preparation, stabilization, and use of catalysts containing metal ion - metal nanocluster ensemble sites. We shall discuss different case studies summarized in Table 1. 

In the present review the role of supported metal ion - metal nanocluster ensemble sites in activity and selectivity control of different catalytic reactions will be discussed. Evaluation of literature data and interpretation of author s recent results obtained in the activation of different organic carbonyl compounds, nitriles, and the CO molecule will be given. The catalytic performance of metallic nanoclusters promoted by metal ions or reducible metal oxides will be discussed in separate chapters according to the type of metal forming the nanocluster. 

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