Corrosion of Ba1−xSrxCo1−yFeyO3−δ and La0.3Ba0.7Co0.2Fe0.8O3−δ materials for oxygen separating membranes under Oxycoal conditions

The perovskite-type ceramics Ba0.3Sr0.7Co0.2Fe0.8O3−δ, Ba0.5Sr0.5Co0.8Fe0.2O3−δand La0.3Ba0.7Co0.2Fe0.8O3−δ are tested concerning their chemical stability under OXYCOAL–AC process conditions. Uniaxially pressed pellets are annealed in three different atmospheres consisting of N2/O2/CO2 (200 h), CO2/H2O/O2 and CO2/H2O/O2/SO2 (96 h) in a temperature range of 600–800 imageC. The samples annealed in the atmospheres containing water vapour are covered on the top with Na2CO3 and an eutectic mixture of Na2SO4 and K2SO4, respectively. The specimens are characterised using light microscopy (LM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). In addition, powders of the perovskite material are mixed up with Na2CO3 and Na2SO4/K2SO4, respectively, annealed under the same conditions and analysed by X-Ray Diffraction (XRD) for a well-defined identification of the corrosion products detected by SEM/EDX. Ba0.5Sr0.5Co0.8Fe0.2O3−δ is the only material affected by N2/O2/CO2. The other atmospheres and the deposits cause severe corrosion on all three materials.