The Fixed Bed Experimental Study Of A O₂/CO₂Production Using Perovskite-type Oxides

O₂/CO₂recycle combustion has obtained wildly attentions for its great potential onreducing CO₂emissions. The major barriers for the application of this technology is theexpensive equipment investment and oxygen generation costs. Perovskite-type sorbentshave been identified as the ideal sorbent for high temperature oxygen separation process,and it is important to understand the mechanism of this process and find the best sorbents.Perovskite-type oxides are found to be good electronic and ionic mixed conductingmaterials, and have great potential application in environmental protection, catalysis,oxygen carriers fields. In this paper, we used two different sol-gel methods to prepare allthe samples which are EDTA-NH₄OH method and citric acid method, respectively. X-raydiffraction （XRD） analysis results showed that the EDTA-NH₄OH method is good forcrystal growth and particle size distribution is more homogeneous.Fixed-bed experiments were performed to study the oxygen separation performance.The reactor outlet oxygen concentration and oxygen desorption ability of four differentperovskite-type oxides react with CO₂was studied by gas analyser. The results indicatesthat the novel BSCF shows the best oxygen desorption ability among them.BSCF and SrCo0.8Fe0.2O3-δ（SCF） characteristic of reaction were studied andcompared. The experimental results indicate that the pretreatment condition of800℃for1h is optimal for the fresh BSCF sample and SCF. And the best desorption temperature is870℃for BSCF while it is850℃for SCF. All the perovskite oxides show good recycleability. The X ray diffraction shows that BSCF have a high convention after30minutesreaction with CO₂, and after one cycle reaction, BSCF can return to its original phasecompletely．Finally, the value of oxygen nonstoichiometry δ of BSCF and SCF was measured byiodometric titration method．So the reaction equation can be described exactly．The resultindicates that theoretic oxygen desorption ability of SCF is better that BSCF, but theexperimental results shows BSCF has a better oxygen desorption ability.