Theoretical basis of isotopic oxygen exchange in a gas-solid oxide system are considered. A generalized model is suggested that accounts for diffusion of tracer oxygen atoms and allows within a single approach to perform numeric analysis of isotope experiments implemented in reactors of various types and in different temperature modes. It is shown that when C18O2 is used as an isotopic reagent, the oxygen exchange rate on the metal oxide surface increases manifold (as compared to 18O2), which allows determining more precisely diffusion limitations in case of isotopic exchange of oxygen in the oxide bulk. Estimates of oxygen self-diffusion coefficients are obtained in dispersed systems based on doped cerium-zirconium oxides with a fluorite-type structure, doped lanthanum silicates with an apatite-type structure, and also mixed praseodymium nickelates-cobaltites and their composites with yttrium-doped ceria.
- doped cerium-zirconium oxides
- doped lanthanum silicates
- isotopic exchange of oxygen
- mixed praseodymium nickelates-cobaltites