Mossbauer spectra and catalytic behavior of perovskite-like SrFe0.7Al0.3O3-delta
authors Kharton, VV; Waerenborgh, JC; Rojas, DP; Yaremchenko, AA; Valente, AA; Shaula, AL; Patrakeev, MV; Marques, FMB; Rocha, J
nationality International
journal CATALYSIS LETTERS
author keywords methane oxidation; Mossbauer spectroscopy; strontium ferrite; membrane reactor; synthesis gas; oxygen nonstoichiometry; mixed conductor
keywords METHANE OXIDATION; OXYGEN; SURFACE; GAS; TECHNOLOGIES; CONVERSION; STABILITY; VACANCIES
abstract Mixed-conducting SrFe0.7Al0.3O3-delta (SFA) exhibits substantial catalytic activity towards partial oxidation of methane and can thus be considered as a component of monolithic ceramic reactors for synthesis gas generation, where the dense membrane and porous catalyst at the permeate-side surface are made of similar compositions. Surface modification of SFA powder and membranes with Pt has no essential effect on the performance of a model reactor, suggesting that the catalytic behavior of SFA is mainly determined by the surface states of iron and oxygen ions in the catalyst. The Mossbauer spectroscopy shows that reduction of SrFe0.7Al0.3O3-delta, having cubic perovskite lattice in air, leads to the co-existence of perovskite- and brownmillerite-like domains, whilst the concentrations of metallic Fe and even Fe2+ under typical operation conditions are lower than the detection limits. The amount of vacancy-ordered phase increases with decreasing oxygen content, the estimations of which were confirmed by coulometric titration data. The catalytic activity of ferrite-based materials may thus be associated with lattice instability characteristic of morphotropic phase transformations.
publisher SPRINGER
issn 1011-372X
year published 2005
volume 99
issue 3-4
beginning page 249
ending page 255
digital object identifier (doi) 10.1007/s10562-005-2131-7
web of science category Chemistry, Physical
subject category Chemistry
unique article identifier WOS:000226758400022
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