resumo
Analysis of oxygen permeation fluxes through Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) capillary membranes, fabricated via a phase-inversion spinning technique using polysulfone as binder, showed a significant limiting role of the surface-oxygen exchange kinetics. Within the studied temperature and oxygen partial pressure ranges, the activation of core and shell sides of the BSCF capillary with praseodymium oxide (PrOx) resulted in an increase in permeation rate of about 300%. At 1123-1223K the activated BSCF membranes demonstrate almost 3-times lower activation energies for the overall oxygen transport (similar to 35 kJ/mol) than the non-activated capillaries, indicating that the mechanism of oxygen transport through the activated capillaries becomes significantly controlled by bulk diffusion limitations, allowing further improvement of the overall performance by decreasing the wall thickness. XRD, EDS and EPMA studies revealed the formation of (Pr,Ba,Sr)(Co,Fe)O3-delta perovskite-type oxides on the surface of the PrOx-modified membranes, which may be responsible for the drastic increase in oxygen exchange rate. At T> 1123 K both non-activated and activated Ba0.5Sr0.5Co0.8Fe0.2O3-delta membranes demonstrate stable performance with time, while at 1073K only a small initial decrease in permeation was observed. (C) 2010 Elsevier B.V. All rights reserved.
palavras-chave
HOLLOW-FIBER MEMBRANES; PERMEABLE MEMBRANE; AIR SEPARATION; PERMEATION; PEROVSKITE; PERFORMANCE; STABILITY; CONDUCTIVITY; CATHODES; SYNGAS
categoria
Engineering; Polymer Science
autores
Kovalevsky, A; Buysse, C; Snijkers, F; Buekenhoudt, A; Luyten, J; Kretzschmar, J; Lenaerts, S
nossos autores
Andrei Kavaleuski
Investigador principalagradecimentos
This work was supported by the German Helmholtz Alliance Project