Design Principles of Perovskites for Thermochemical Oxygen Separation

Separation and concentration of O2 from gas mixtures is central to several sustainable energy technologies, such as solar‐driven synthesis of liquid hydrocarbon fuels from CO2, H2O, and concentrated sunlight. We introduce a rationale for designing metal oxide redox materials for oxygen separation th...

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Bibliographic Details
Published in:	ChemSusChem Vol. 8; no. 11; pp. 1966 - 1971
Main Authors:	Ezbiri, Miriam, Allen, Kyle M., Gàlvez, Maria E., Michalsky, Ronald, Steinfeld, Aldo
Format:	Journal Article
Language:	English
Published:	Weinheim WILEY-VCH Verlag 08-06-2015 WILEY‐VCH Verlag Wiley Subscription Services, Inc
Subjects:	Calcium Compounds - chemistry Charge transfer Copper oxides density functional theory Electronic structure Energy technology Gas mixtures Heat exchange Hydrocarbon fuels Lattice vacancies Metal oxides Models, Molecular Molecular Conformation Oxides - chemistry Oxygen Oxygen - chemistry Oxygen - isolation & purification oxygen evolution oxygen reduction Perovskites Pressure Process heat Separation Temperature thermochemical o2 separation Thermogravimetric analysis Titanium - chemistry perovskites thermochemical o2 separation oxygen evolution oxygen reduction density functional theory
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Summary:	Separation and concentration of O2 from gas mixtures is central to several sustainable energy technologies, such as solar‐driven synthesis of liquid hydrocarbon fuels from CO2, H2O, and concentrated sunlight. We introduce a rationale for designing metal oxide redox materials for oxygen separation through “thermochemical pumping” of O2 against a pO2 gradient with low‐grade process heat. Electronic structure calculations show that the activity of O vacancies in metal oxides pinpoints the ideal oxygen exchange capacity of perovskites. Thermogravimetric analysis and high‐temperature X‐ray diffraction for SrCoO3−δ, BaCoO3−δ and BaMnO3−δ perovskites and Ag2O and Cu2O references confirm the predicted performance of SrCoO3−δ, which surpasses the performance of state‐of‐the‐art Cu2O at these conditions with an oxygen exchange capacity of 44 mmol O 2 mol SrCoO 3−δ−1 exchanged at 12.1 μmol O 2 min−1 g−1 at 600–900 K. The redox trends are understood due to lattice expansion and electronic charge transfer. Heat and pump thermochemically: Gas‐phase O2 separation often limits the solar‐to‐fuel energy conversion efficiency of solar‐driven thermochemical H2O and CO2 splitting. A method is proposed by which O2 is separated from gas mixtures through “pumping” O2 against a partial pressure gradient using metal oxide redox materials and low‐temperature solar‐thermal process heat. Design principles for perovskite reactants are developed and demonstrated.
Bibliography:	ETH Zürich ArticleID:CSSC201500239 ark:/67375/WNG-Q3LBWQKZ-N Swiss Federal Office of Energy - No. SI/500660-01 Swiss Competence Center Energy & Mobility European Union's ERC Advanced Grant - No. 320541 Helmholtz-Gemeinschaft Deutscher Forschungszentren (Virtuelles Institut SolarSyngas) istex:82EE13CE7406A243E1D11F770A62E3AFDA5E6F5B ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1864-5631 1864-564X
DOI:	10.1002/cssc.201500239