Processing and characterization of La0.5Sr0.5FeO3-supported Sr1-xFe(Al)O-3-SrAl2O4 composite membranes
authors Kovalevskya, AV; Kharton, VV; Maxim, F; Shaula, AL; Frade, JR
nationality International
journal JOURNAL OF MEMBRANE SCIENCE
author keywords asymmetric membrane; mixed conductor; oxygen permeability; thermal expansion; ferrite
keywords OXYGEN SEPARATION MEMBRANES; PEROVSKITE-TYPE OXIDES; IONIC TRANSPORT; CERAMIC MEMBRANES; METHANE OXIDATION; SYNGAS PRODUCTION; SYNTHESIS GAS; PERMEABILITY; STABILITY; CONDUCTIVITY
abstract Perovskite-type La0.5Sr0.5FeO3-delta and composite Sr0.77Fe0.54Al0.46O2.54-delta exhibit relatively high oxygen permeation fluxes and similar thermal expansion coefficients, (12.4-13.1) x 10(-6) K-1 at 350-950 K and (23.4-23.7) x 10-6 K-1 at 950-1300 K in air. Due to higher sinterability of Sr0.77Fe0.54Al0.46O2.54-delta consisting of strontium-deficient Sr(Fe, Al)O3-delta perovskite and SrAl2O4 phases, such properties enable to combine these materials in asymmetric membranes where dense Sr0.77Fe0.54Al0.46O2.54-delta layer is supported by porous lanthanum-strontium ferrite ceramics. In order to achieve a sufficient porosity and mechanical strength of the supports, various pore-forming agents were tested, including graphite, methylcellulose powder and an aqueous methylcellulose solution. The asymmetric membranes were fabricated adding 2 wt.% graphite into pre-synthesized La0.5Sr0.5FeO3-delta powder, with subsequent co-pressing and co-sintering at 1723 K. As oxygen permeation through Sr0.77Fe0.54Al0.46O2.54-delta ceramics is substantially affected by the oxygen exchange kinetics, the surface of the dense layer can be effectively activated applying a mixture of the composite, metallic Pt and/or praseodymium oxide. At 1023-1173 K the oxygen fluxes through a model asymmetric membrane, with dense layer thickness of 0.5 mm, varied in the range (1-3) x 10(-7) mol s(-1) cm(-2) under the oxygen partial pressure gradient of 21/2.1 kPa. (c) 2005 Elsevier B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0376-7388
year published 2006
volume 278
issue 1-2
beginning page 162
ending page 172
digital object identifier (doi) 10.1016/j.memsci.2005.10.052
web of science category Engineering, Chemical; Polymer Science
subject category Engineering; Polymer Science
unique article identifier WOS:000238409300018
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journal impact factor 7.183
5 year journal impact factor 7.158
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