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This content will become publicly available on May 16, 2017

Title: Oxygen storage properties of La1-xSrxFeO3-δ for chemical-looping reactions–An in-situ neutron and synchrotron X-ray study

Oxygen storage materials (OSMs) provide lattice oxygen for a number of chemical-looping reactions including natural gas combustion and methane reforming. La1–xSrxFeO3-δ has shown promise for use as an OSM in methane reforming reactions due to its high product selectivity, fast oxide diffusion, and cycle stability. Here, we investigate the structural evolution of the series La1–xSrxFeO3-δ for x = 0, 1/3, 1/2, 2/3, and 1, using in situ synchrotron X-ray and neutron diffraction, as it is cycled under the conditions of a chemical-looping reactor (methane and oxygen atmospheres). In the compositions x = 1/3, 1/2, 2/3, and 1, we discover an envelope , or temperature range, of oxygen storage capacity (OSC), where oxygen can easily and reversibly be inserted and removed from the OSM. Our in situ X-ray and neutron diffraction results reveal that while samples with higher Sr contents had a higher OSC, those same samples suffered from slower reaction kinetics and some, such as the x = 1/2 and x = 2/3 compositions, had local variations in Sr content, which led to inhomogeneous regions with varying reaction rates. Therefore, we highlight the importance of in situ diffraction studies, and we propose that these measurements are required for the thoroughmore » evaluation of future candidate OSMs. Furthermore, we recommend La2/3Sr1/3FeO3-δ as the optimal OSM in the series because its structure remains homogeneous throughout the reaction, and its OSC envelope is similar to that of the higher doped materials.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3]
  1. Univ. of Maryland, College Park, MD (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
1261333
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 28; Journal Issue: 11; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY