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C. Knoll, D. Müller, M. Harasek, P. Weinberger:
"Transition Metal Oxide Redox Couples for High Temperature Thermochemical Energy Storage";
Poster: 32. Workshop Novel Materials and Superconductivity, Obertraun; 12.02.2017 - 18.02.2017.

Oxides of metals with different accessible oxidation states are considered as auspicious candidates for high-temperature thermochemical energy storage (TCES) materials. As the most promising candidates regarding energy content and equilibrium temperature, Co₃O₄, as well as MnO₂ and PbO₂ were identified via a systematic database search. To shed light on the boundary conditions regarding temperature profile and
O₂-concentration, measurements using O₂, air and N₂ atmosphere - followed by reoxidation under O₂ - were performed. Whereas for the Co₃O₄ system only a moderate influence of the O₂-concentration was observed, for the Mn₂O₃ system a notable impact on the reaction temperatures is given.
According to the stability regimes of the intermediate phases under various atmospheres an isothermal TCES-cycle for Co₃O₄ and Mn₂O₃ was investigated, showing that under isothermal conditions the redox-process was triggered by a change in the reactive-gas atmosphere.
By application of a gas-change design for the redox-cycle a significant down-shift of the reaction temperatures compared to the temperature triggered redox reaction could be achieved, which allows first for the application of the materials in form of a chemical heat pump, as well as for a broadened operational profile not only in combination with concentrating solar power plants, but also with recycling of flue gas heat.

transition metal oxides, redox reactions, thermochemical energy storage

http://publik.tuwien.ac.at/files/publik_258581.pdf