Fluidized vacancies

Significant Structure Theory and Eucken s Polymer Model. If we drop the restriction that the bulky species represent only Ice-I-like structures and reserve the term ice-like for water molecules which have merely the same spatial arrangement as ice (i.e., tetrahedrally hydrogen-bonded), we may include in this two-state theory (in which we have a bulky and a dense species) the treatment by Marchi and Eyring (107). This is a special case of the significant structure theory of liquids and introduces, as a specific element, fluidized vacancies in addition to the individual monomers (which, in turn, are assumed capable of free rotation). 

This chapter outlines one possible interpretation of the nature of the fluidized vacancies. They are assumed to be thin layers of void space between the small crystalline domains in the liquid. Based on the Gruneisen potential function, the nature of the gap between crystalline doiiiains is investigated and is found to be an interval of no barriers to atomic translation. 

Alternatively, the sub-surface or bulk 0 species may diffuse to the surface to refill the vacancy. Note that only reactors operating in a redox decoupling mode, like CFBs, would derive oxygen from the bulk because the oxidation step is carried out in a distinct fluidized-bed reactor. Obviously this diffusion process is slower than the surface re-oxidation by molecular (gaseous) O2, but depending on the cation reducibihty during catalyst equilibration , part of the bulk becomes reduced. At the steady state (rR = rred = Tox) there is a hmited amount of 0 species able to participate in the reaction at each cycle (turn-over). 

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