The use of strontium ferrite in chemical looping systems
Clare P. Grey and
Stuart A. Scott
Applied Energy, 2018, vol. 223, issue C, 369-382
This work reports a detailed chemical looping investigation of strontium ferrite (SrFeO3−δ), a material with the perovskite structure type able to donate oxygen and stay in a nonstoichiometric form over a broad range of oxygen partial pressures, starting at temperatures as low as 250°C (reduction in CO, measured in TGA). SrFeO3−δ is an economically attractive, simple, but remarkably stable material that can withstand repeated phase transitions during redox cycling. Mechanical mixing and calcination of iron oxide and strontium carbonate was evaluated as an effective way to obtain pure SrFeO3−δ. In–situ XRD was performed to analyse structure transformations during reduction and reoxidation. Our work reports that much deeper reduction, from SrFeO3−δ to SrO and Fe, is reversible and results in oxygen release at a chemical potential suitable for hydrogen production. Thermogravimetric experiments with different gas compositions were applied to characterize the material and evaluate its available oxygen capacity. In both TGA and in-situ XRD experiments the material was reduced below δ = 0.5 followed by reoxidation either with CO2 or air, to study phase segregation and reversibility of crystal structure transitions. As revealed by in-situ XRD, even deeply reduced material regenerates at 900°C to SrFeO3–δ with a cubic structure. To investigate the catalytic behaviour of SrFeO3−δ in methane combustion, experiments were performed in a fluidized bed rig. These showed SrFeO3−δ donates O2 into the gas phase but also assists with CH4 combustion by supplying lattice oxygen. To test the material for combustion and hydrogen production, long cycling experiments in a fluidized bed rig were also performed. SrFeO3−δ showed stability over 30 redox cycles, both in experiments with a 2-step oxidation performed in CO2 followed by air, as well as a single step oxidation in CO2 alone. Finally, the influence of CO/CO2 mixtures on material performance was tested; a fast and deep reduction in elevated pCO2 makes the material susceptible to carbonation, but the process can be reversed by increasing the temperature or lowering pCO2.
Keywords: Chemical looping combustion; CLC; Hydrogen production; Perovskite; Strontium ferrite; Oxygen carrier (search for similar items in EconPapers)
References: View references in EconPapers View complete reference list from CitEc
Citations Track citations by RSS feed
Downloads: (external link)
Full text for ScienceDirect subscribers only
This item may be available elsewhere in EconPapers: Search for items with the same title.
Export reference: BibTeX
RIS (EndNote, ProCite, RefMan)
Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:223:y:2018:i:c:p:369-382
Ordering information: This journal article can be ordered from
http://www.elsevier. ... 405891/bibliographic
Access Statistics for this article
Applied Energy is currently edited by J. Yan
More articles in Applied Energy from Elsevier
Bibliographic data for series maintained by Dana Niculescu ().