Stability and oxygen transport properties of BaCo0.8-xFexNb0.2O3-δ perovskite membranes in CO2-containing atmosphere
|Jianxin Yi , Michael Schroeder|
Institute of Physical Chemistry, RWTH-Aachen University, Landolltweg 2, Aachen 52074, Germany
Dense perovskite-type ceramic membranes made from mixed oxygen ionic-electronic conductors (MIEC) have received much attention due to the high selectivity for oxygen separation. Using an MIEC membrane system for the pure oxygen supply benefits an oxy-fuel power plant with a significant increase in the efficiency, compared with the conventional route by cryogenic air separation. For such application, membranes with sufficient long-term stability under the desired working conditions, that is, in atmospheres containing aggressive gases like CO2 and H2O etc., and at temperatures typically above 700 °C, are crucial. Some perovskite-type membranes with high oxygen permeability have recently been shown to be susceptible to the presence of these aggressive gases.
In order to better understand how the presence of CO2 affects the performance of the perovskite oxides and to explore strategy for development of CO2-resistant materials, BaCo0.8-xFexNb0.2O3-δ (x=0.2-0.8) perovskite membranes were prepared and their oxygen permeability and stability in CO2 were investigated. The oxygen permeation fluxes were measured with pure CO2 as sweep gas and compared with those measured with Ar. Degradation in the oxygen fluxes was observed when CO2 was used. The stability of the materials was also examined by a series of CO2 annealing experiments under various conditions and the results of the (micro-)structural analyses for the annealed samples will be presented. The behaviour of the membranes in CO2 is linked with the B-site cation composition of the perovskites.
Presentation: Oral at E-MRS Fall Meeting 2009, Symposium G, by Jianxin Yi
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-05-11 13:49 Revised: 2009-06-07 00:48