Iron catalysts gold nanoparticles

The initial rates of CO oxidation were determined on the samples treated in different ways. The reactivity of the samples investigated in the preliminary experiments decreases in the sequence of Au/FeO c/SiO (/Si(l 0 0) > FeO / SiO,/Si(10 0)>Au/Si02/Si(100)>Si(100). The Au/ Fe0 c/Si02/Si(l 0 0) catalyst has the highest initial activity. The results along with XPS and TEM data demonstrate that the interaction of gold nanoparticles and iron oxide tends to stabilize the metal character of gold and due to this stabilization, the Au/FeO catalyst has enhanced activity in the CO oxidation. 

Three series of Au nanoparticles on oxidic iron catalysts were prepared by coprecipitation, characterized by Au Mossbauer spectroscopy, and tested for their catalytic activity in the room-temperature oxidation of CO. Evidence was found that the most active catalyst comprises a combination of a noncrys-taUine and possibly hydrated gold oxyhydroxide, AUOOH XH2O, and poorly crystalhzed ferrihydrate, FeH0g-4H20 [421]. This work represents the first study to positively identify gold oxyhydroxide as an active phase for CO oxidation. Later, it was confirmed that the activity in CO2 production is related with the presence of-OH species on the support [422]. 

A novel preparation method was developed for the preparation of iron and gold/iron supported eatalysts using metaUic carbonyl clusters as precursors of highly dispersed nanoparticles over Ti02 and Ce02. A series of catalysts with different metal loadings were prepared and tested in the complete oxidation of methanol and the preferential oxidation of CO in the presence of H2 (PROX) as model reactions. The characterization by BET, XRD, TEM, H2-TPR, ICP-AES and XPS spothghts the interaction between Au and Fe and their influence on the catalytic activity. 

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. 

Wang, C.-T. and Ro, S.-H. (2006) Surfece nature of nanoparticle gold/iron oxide aerogel catalysts. J. Non-Cryst. Solids,... 

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