Functional Oxides for Oxygen Scavenging Applications
Abstract
The aim of this experimental study is to develop oxide-based materials for oxygen
enrichment/separation from air through pressure/temperature swing sorption. Production
of commercial oxygen is conventionally achieved through cryogenic distillation of air
into its components, which requires large capital investment and energy consumption.
Other methods like polymeric membrane separation and pressure swing adsorption are
used for small to medium size (1-400 Nm3/h) demand of oxygen. As an alternative,
membrane separation with the use of mixed ionic/electronic conducting oxide ceramics
offer infinitely high perm-selectivity compared to other separation processes.
Certain non-stoichiometric transition metal oxides can reversibly incorporate or release
oxygen from their lattice by changing the ambient conditions. A change in oxygen
partial pressure or temperature of the surrounding can influence the oxygen content in
their lattice. Thus, switching of ambient partial pressure of oxygen from low to high
can incorporate oxygen selectively into the lattice and vice versa, achieving an efficient
separation of oxygen from air.
Transition metal Perovskite oxides (general formula ABO3) and related structures
are notable candidates in this regard. They have a relatively open structure of corner
shared octahedra with variable oxide ion vacancies that can be tuned by synthesis methods
and chemistry. Perovskite and double perovskite oxides such as SrCoO3d and (RE)BaCo2O5+d (RE = Dy, Y) respectively have been explored for oxygen separation
applications in this thesis