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Title: Surface analysis of mixed-conducting ferrite membranes by the conversion-electron Moessbauer spectroscopy

Abstract

Conversion-electron Moessbauer spectroscopy analysis of iron surface states in the dense ceramic membranes made of {sup 57}Fe-enriched SrFe{sub 0.7}Al{sub 0.3}O{sub 3-{delta}} perovskite, shows no traces of reductive decomposition or carbide formation in the interfacial layers after operation under air/CH{sub 4} gradient at 1173 K, within the limits of experimental uncertainty. The predominant trivalent state of iron cations at the membrane permeate-side surface exposed to flowing dry methane provides evidence of the kinetic stabilization mechanism, which is only possible due to slow oxygen-exchange kinetics and enables long-term operation of the ferrite-based ceramic reactors for natural gas conversion. At the membrane feed-side surface exposed to air, the fractions of Fe{sup 4+} and Fe{sup 3+} are close to those in the powder equilibrated at atmospheric oxygen pressure, suggesting that the exchange limitations to oxygen transport are essentially localized at the partially reduced surface. - Graphical Abstract: Conversion-electron Moessbauer spectroscopy analysis of dense ceramic membranes made of {sup 57}Fe-enriched SrFe{sub 0.7}Al{sub 0.3}O{sub 3-{delta}} perovskite, shows no reductive decomposition in thin interfacial layers after testing under air/CH{sub 4} gradient, enabling stable operation of the ferrite-based ceramic reactors for partial oxidation of methane. Highlights: > Conversion-electron Moessbauer spectroscopy is used for mixed-conducting membranes. > No decompositionmore » is detected in the membrane surface layers under air/CH{sub 4} gradient. > Due to kinetic stabilization, Fe{sup 3+} states prevail at the surface exposed to methane. > Transmission Moessbauer spectra show perovskite decomposition on equlibration in CH{sub 4}. > Ferrite-based ceramic reactors can stably operate under air/CH{sub 4} gradient.« less

Authors:
;  [1];  [2];  [2]
  1. Chemistry Department, Instituto Tecnologico e Nuclear, CFMC-UL, EN 10, 2686-953 Sacavem (Portugal)
  2. Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)
Publication Date:
OSTI Identifier:
21580247
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 184; Journal Issue: 9; Other Information: DOI: 10.1016/j.jssc.2011.07.003; PII: S0022-4596(11)00372-0; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Journal ID: ISSN 0022-4596
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CARBIDES; CERAMICS; DECOMPOSITION; FERRITE; FERRITES; IRON 57; IRON IONS; LAYERS; MEMBRANES; METHANE; MOESSBAUER EFFECT; NATURAL GAS; OXYGEN; PEROVSKITE; SURFACES; ALKANES; ALLOYS; CARBON ADDITIONS; CARBON COMPOUNDS; CHARGED PARTICLES; CHEMICAL REACTIONS; ELEMENTS; ENERGY SOURCES; EVEN-ODD NUCLEI; FERRIMAGNETIC MATERIALS; FLUIDS; FOSSIL FUELS; FUEL GAS; FUELS; GAS FUELS; GASES; HYDROCARBONS; INTERMEDIATE MASS NUCLEI; IONS; IRON ALLOYS; IRON COMPOUNDS; IRON ISOTOPES; ISOTOPES; MAGNETIC MATERIALS; MATERIALS; MINERALS; NONMETALS; NUCLEI; ORGANIC COMPOUNDS; OXIDE MINERALS; OXYGEN COMPOUNDS; PEROVSKITES; STABLE ISOTOPES; TRANSITION ELEMENT ALLOYS; TRANSITION ELEMENT COMPOUNDS

Citation Formats

Waerenborgh, J.C., Tsipis, E.V., Yaremchenko, A.A., and Kharton, V.V., E-mail: kharton@ua.pt. Surface analysis of mixed-conducting ferrite membranes by the conversion-electron Moessbauer spectroscopy. United States: N. p., 2011. Web. doi:10.1016/j.jssc.2011.07.003.
Waerenborgh, J.C., Tsipis, E.V., Yaremchenko, A.A., & Kharton, V.V., E-mail: kharton@ua.pt. Surface analysis of mixed-conducting ferrite membranes by the conversion-electron Moessbauer spectroscopy. United States. doi:10.1016/j.jssc.2011.07.003.
Waerenborgh, J.C., Tsipis, E.V., Yaremchenko, A.A., and Kharton, V.V., E-mail: kharton@ua.pt. Thu . "Surface analysis of mixed-conducting ferrite membranes by the conversion-electron Moessbauer spectroscopy". United States. doi:10.1016/j.jssc.2011.07.003.
@article{osti_21580247,
title = {Surface analysis of mixed-conducting ferrite membranes by the conversion-electron Moessbauer spectroscopy},
author = {Waerenborgh, J.C. and Tsipis, E.V. and Yaremchenko, A.A. and Kharton, V.V., E-mail: kharton@ua.pt},
abstractNote = {Conversion-electron Moessbauer spectroscopy analysis of iron surface states in the dense ceramic membranes made of {sup 57}Fe-enriched SrFe{sub 0.7}Al{sub 0.3}O{sub 3-{delta}} perovskite, shows no traces of reductive decomposition or carbide formation in the interfacial layers after operation under air/CH{sub 4} gradient at 1173 K, within the limits of experimental uncertainty. The predominant trivalent state of iron cations at the membrane permeate-side surface exposed to flowing dry methane provides evidence of the kinetic stabilization mechanism, which is only possible due to slow oxygen-exchange kinetics and enables long-term operation of the ferrite-based ceramic reactors for natural gas conversion. At the membrane feed-side surface exposed to air, the fractions of Fe{sup 4+} and Fe{sup 3+} are close to those in the powder equilibrated at atmospheric oxygen pressure, suggesting that the exchange limitations to oxygen transport are essentially localized at the partially reduced surface. - Graphical Abstract: Conversion-electron Moessbauer spectroscopy analysis of dense ceramic membranes made of {sup 57}Fe-enriched SrFe{sub 0.7}Al{sub 0.3}O{sub 3-{delta}} perovskite, shows no reductive decomposition in thin interfacial layers after testing under air/CH{sub 4} gradient, enabling stable operation of the ferrite-based ceramic reactors for partial oxidation of methane. Highlights: > Conversion-electron Moessbauer spectroscopy is used for mixed-conducting membranes. > No decomposition is detected in the membrane surface layers under air/CH{sub 4} gradient. > Due to kinetic stabilization, Fe{sup 3+} states prevail at the surface exposed to methane. > Transmission Moessbauer spectra show perovskite decomposition on equlibration in CH{sub 4}. > Ferrite-based ceramic reactors can stably operate under air/CH{sub 4} gradient.},
doi = {10.1016/j.jssc.2011.07.003},
journal = {Journal of Solid State Chemistry},
issn = {0022-4596},
number = 9,
volume = 184,
place = {United States},
year = {2011},
month = {9}
}