Effects of scandium doping concentration on the properties of strontium cobalt oxide membranes

AUTOR(ES)

Zeng, Pingying, Ran, Ran, Shao, Zongping, Yu, Hai, Liu, Shaomin

FONTE

Brazilian Journal of Chemical Engineering

DATA DE PUBLICAÇÃO

2009-09

RESUMO

Perovskite-type mixed conducting oxides of SrCo1-ySc yO3-δ (y=0.02-0.7) were synthesized by a combined EDTA-citrate complexing method. Different scandium doping concentrations in SrCo1-ySc yO3-δ have significant effects on the phase structure, electrical conductivity, surface properties and oxygen permeation behaviour of the resultant membranes. SrCoO3-δ without scandium incorporation displayed a 2H BaNiO3-type structure with almost zero oxygen flux at high temperatures. Small amounts of Sc2O3 doping (y<0.1) efficiently stabilized the oxide in a cubic perovskite structure, leading to a sharp increase in the permeation flux, with a maximum value of 3.1ml.cm-2.min-1 achieved at 900ºC for SrCo0.95Sc0.05O3-δ and SrCo0.9Sc0.1O3-δ membranes. The permeation process could be rate-limited by either the oxygen bulk diffusion, oxygen surface exchange, or a combination of both depending on the scandium doping level. Further increases of the Sc3+ doping concentration (y>0.1) were found to lower the membrane oxygen fluxes, with y³≥0.4 doped SrCo1-ySc yO3-δ ceramics no longer showing any oxygen permeation.

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