Redox migration oxygen properties

The substitution of transition metals such as Fe in the Ce02 fluorite structure, for example, results in a higher catalytic activity due to the combination of different cations in the oxide matrix, which produces materials with new electronic, structural, textural, and redox migration oxygen properties [4-6]. 

The reductive/oxidative properties of transitional metal elements in these zeolite catalysts were also examined by TPR and TPO, and it is shown that metallic species in certain cation locations may migrate under calcination, reduction, and reaction conditions [7], The different treatment, e g, coking or even the oxidative regeneration, will produce metallic species of varied oxidation states with different distributions in the molecular sieve structures as exemplified by the above XPS data. The redox properties of these metallic cations exhibit the influence of hydrogen and/or coke molecules, and it is further postulated that the electron transfer with oxygen species are considered responsible for their catalyzed performance in the TPO regeneration processes, as shown in Figure 2. 

These simulation studies, based on either static lattice, MD or ab initio methods, have been able to provide deeper insight as to the fundamental solid state properties at the atomic level, particularly in the following key areas (a) defect chemistry and dopant-vacancy association, (b) mechanisms of oxygen ion migration, (c) structures and stability of surfaces (mainly (110) and (111)), (d) energetics of redox reactions... 

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