Some Challenging Aspects of These Characterisation Studies

Some Challenging Aspects of These Characterisation Studies 

Section 4.3.2 will be devoted to the chemical characterisation studies. Because of the relationship existing between the support reduction degree and the occurrence of the deactivation phenomena mentioned above, we shall review first some of the major problems to be faced in relation to the redox characterisation of ceria and related oxide supports, sub-section 4.3.2.1. Then, we shall discuss the chemisorptive properties of these catalysts. In particular, section 4.3.2.2, will be devoted to the adsorption of H2 and CO, by far the two most commonly used probe molecules. Special attention will be paid to the relationship existing between chemisorptive behaviour and reduction temperature. We shall also report on some recent hydrogen chemisorption studies, in accordance with which, the sensitivity to the deactivation phenomena may vary from one noble metal to the other (97,117,235), being also influenced by the presence of chlorine in the support (163). 

Finally, some concluding remarks summarising the progress made in the understanding of the strong metal/support interaction phenomena exhibited by the NM/Ce(M)02-x catalysts will be presented in section 4.3.4. 

Chemical Characterisation of M/Ce02 and Closely Related Catalysts 

Many different techniques have been used to probe the redox state of ceria and related oxide systems both in the presence and in the absence of a supported metal phase EPR (5,46,94,95,189,227,326,327), XPS (132,166,177,179,193,199,224,289,328-330), 

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