(515b) Double Perovskite Materials for Applications in Chemical Looping and Oxygen Storage

Chemical looping combustion is a process currently being
studied for its potential to reduce the energy penalty associated with carbon
capture. To reduce this energy penalty, chemical looping makes use of metal
oxides as the source of oxygen for combustion of a fuel. The resulting waste
stream consists only of CO₂ and water. The water can then be
condensed resulting in a pure CO₂ stream ready for sequestration.
One interesting class of materials for chemical looping applications are double
perovskite oxides due to their ability to rapidly
store and release oxygen. Previously, the double perovskite
BaYMn₂O_5+xwas shown to rapidly
and reversibly store and release oxygen with unprecedented kinetics. The
ability of these materials to store and release oxygen is derived from the fact
that the cations in these materials can vary in
oxidation state which allows the oxygen stoichiometry
to vary. Altering the cation composition in these
materials will allow for the optimization of both the amount of oxygen stored
and the storage/release kinetics. Four double perovskite
materials were synthesized and studied for this work, BaLaFe₂O_5+x,
BaLaCo₂O_5+x, BaYCo₂O_5+x and BaYFe₂O_5+x.
Characterization of the materials using X-ray diffraction and X-ray
photoelectron spectroscopy will be presented. We will also present adsorption/desorption
studies and basic kinetic data as well as initial results of testing with
methane as a model fuel. The Fe-containing compounds have proven to be the most
interesting as they are stable for multiple adsorption/desorption
cycles with both nitrogen/air and hydrogen/air at multiple temperatures.