Oxygen storage and release capacity ,

The CeO CejOs System The redox properties ofceria and ceria-based materials have been studied in great detail because of their oxygen storage and release capacities, which are highly relevant for their application in modem three-way automotive catalysts [6, 7]. Unfortunately, the temperatures used in these studies are usually far lower than those necessary for thermal reduction in inert atmospheres. Therefore, the applicability of these data must be regarded as limited. Some case studies of ceria-based systems in solarthermal cycles are published in the literature [2,4,14] ... 

Oxygen storage and release capacity 169 reducing atmosphere 232... 

The book starts with a detailed and fundamental structural characterization of the main ceria-based materials (Chapter 1), followed by a careful overview of recent achievements in ffR-TEM characterization (Chapter 2). Chapter 3 gives an insight into the oxygen storage and release capacity of both model and commercial ceria-containing three-way catalysts, which is one of the key properties in their successful application. A discussion of the role of ceria-based materials in the activation and conversion of nitrogen oxides (Chapter 4) closes the first part of the book. 

Injury to cells and tissues may enhance the toxicity of the active oxygen species by releasing intracellular transition metal ions (such as iron) into the surrounding tissue from storage sites, decompartmentalized haem proteins, or metalloproteins by interaction with delocalized proteases or oxidants. Such delocalized iron and haem proteins have the capacity to decompose peroxide to peroxyl and alkoxyl radicals, exacerbating the initial lesion. 

Fig. 14. Oxygen storage capacity and oxygen release rates at 500°C.

Since OSC (Oxygen Storage Capacity) was introduced as a way of determining on quantitative basis the capability of ceria-based supports to release oxygen under reducing conditions, and to uptake it under oxidising conditions (359), numerous studies (35,98,160,180,186,203,249,337,341,354.362-367) have included OSC measurements, as a routine way of characterising the redox properties of these catalytic systems. 

Fig. 16.4 A Phase diagram of the Ce02—Zr02 system [45]. B Schematic views of (a) a nearly fresh catalyst surface and (b) a moderately aged catalyst with high activity, but reduced oxygen storage/release capacity.

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