Methane oxidation over Fe-, Co-, Ni- and V-containing mixed conductors
authors Kharton, VV; Yaremchenko, AA; Valente, AA; Sobyanin, VA; Belyaev, VD; Semin, GL; Veniaminov, SA; Tsipis, EV; Shaula, AL; Frade, JR; Rocha, J
nationality International
journal SOLID STATE IONICS
author keywords methane conversion; synthesis gas; ceramic membrane; mixed conductor; oxygen permeability
keywords CERAMIC MEMBRANE REACTOR; SYNTHESIS GAS; SYNGAS PRODUCTION; DRY METHANE; OXYGEN PERMEABILITY; PEROVSKITE OXIDES; CONVERSION; STABILITY; LA2NI0.9CO0.1O4+DELTA; CONDUCTIVITY
abstract The catalytic oxidation of methane over mixed conducting ceramics, including perovskite-type SrFe0.7Al0.3O3-sigma,5 and La0.3Sr0.7Co0.8Ga0.2O3-sigma, dual-phase composite (SrCo)(0.5)(Sr2Fe3)(0.5)O4.75+/-delta, La2Ni0.9Co0.1O4+delta with K2NiF4-type structure and zircontype CeVO4+delta, is primarily governed by bonding energy between oxygen and transition metal cations, which leads to general correlations between the catalytic activity, oxygen desorption, oxygen ionic transport, thermal expansion, and, often, phase stability. The steady-state conversion of dry CH4 either by oxygen permeating through dense oxide ceramics in a membrane reactor or by atmospheric O-2 (methane/air ratio of 30:70) in a fixed bed reactor with membrane material as catalyst results in high CO2 selectivity, increasing when the oxygen permeability of mixed conductors increases. The prevailing mechanism of total methane combustion makes it necessary to incorporate reforming catalysts in the membrane reactors for natural gas conversion to Synthesis gas (syngas). Dominant CO2 formation is also observed for the oxidation of CH4 Pulses supplied in helium flow over the mixed conductor powders, except for SrFe0.7Al0.3O3-delta yielding synthesis gas with the H-2/CO ratio close to 2, characteristic of the partial oxidation process. For a model reactor comprising one disk-shaped membrane and a catalyst both made of SrFe0.7Al0.3O3-delta, the methane conversion and CO selectivity at 1223 K achieved 65% and 48%, respectively. (C) 2004 Elsevier B.V All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0167-2738
year published 2005
volume 176
issue 7-8
beginning page 781
ending page 791
digital object identifier (doi) 10.1016/j.ssi.2004.10.019
web of science category Chemistry, Physical; Physics, Condensed Matter
subject category Chemistry; Physics
unique article identifier WOS:000227075900019
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journal impact factor 2.751
5 year journal impact factor 2.607
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