Effect of A/B-site substitution on oxygen production performance of strontium cobalt based perovskites for CO2 capture application

Abstract

Oxy-fuel combustion is one of the proposed technologies which have the potential to achieve zero CO₂ emission. Strontium cobalt based perovskite oxygen carriers are promising materials for air separation with a high selectively for oxygen. And these perovskites can produce an oxygen enriched carbon dioxide stream for an oxy-fuel combustion process. The relatively low oxygen production yield may be a drawback of this type of material for this technology. This paper presents an effective approach by A/B-site substitution to improve the oxygen production performance of the perovskites. In this study, a series of different A/B-site substituted SrCo_0.8Fe_0.2O_3−δ were prepared by an EDTA–citrate sol–gel combustion synthesis method. Fixed-bed experiments and TGA measurements were performed to study the effects of A/B-site substitution on cyclic oxygen adsorption/desorption performance of the synthesized samples. The experimental results indicate that the oxygen desorption amounts of different A-site substituted perovskites decrease in the order of BaCo_0.8Fe_0.2O_3−δ > Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ > SrCo_0.8Fe_0.2O_3−δ > Sr_0.5Ca_0.5Co_0.8Fe_0.2O_3−δ > MgCo_0.8Fe_0.2O_3−δ. Moreover, B-site substitution by different transition metal ions can significantly modify oxygen adsorption capacity and oxygen desorption performance of SrCo_0.8Fe_0.2O_3−δ. Furthermore, oxygen desorption performance can be improved when Fe ions of the perovskite SrCo_0.8Fe_0.2O_3−δ are substituted by Zr, Cr, Zn, and Ni ions.