A Novel Analysis of Transient Isothermal 18O Isotopic Exchange on Commercial CexZr1−xO2-Based OSC Materials
Date
2019Author
Vasiliades, Michalis A.Harris, Deb
Stephenson, Hazel
Boghosian, Soghomon
Efstathiou, Angelos M.
ISSN
1572-9028Source
Topics in CatalysisVolume
62Issue
1Pages
219-226Google Scholar check
Metadata
Show full item recordAbstract
A novel methodology for the analysis of 18O2-transient isothermal isotopic exchange (TIIE) response curves obtained over commercial mixed metal oxides upon the gas switch 16O2/Ar (30 min) → 18O2/Kr/Ar (t) at constant T in a flow CSTR micro-reactor in the absence of external and internal mass transport resistances and grain boundary effects, is presented for the first time. The specific aim of this analysis was to derive quantitative descriptors of the16O/18O exchange under pseudo-equilibrium conditions for the transfer rates of oxygen between the gas and solid phases, enabling the assessment of differences in the kinetics of bulk oxygen diffusion over a series of commercial OSC materials used in various catalytic applications (e.g. TWC), without the need of performing any mathematical and kinetic modelling of the surface/bulk oxygen diffusion processes. Based on these descriptors, commercial OSC mixed metal oxides prepared by the same chemical synthesis route but varying the value of one of the synthesis parameters, and having the same at.% composition, were proved to possess largely different transient kinetic rates and other features of the transient response curves of 16O/18O exchange strongly related to the bulk oxygen diffusion in the solids. This novel 18O2-TIIE analysis is quick and provides a reliable means for proving or disproving likely infringement of patented commercial mixed metal oxides OSC materials.