Modification of traditionally impregnated Fe₂O₃/Al₂O₃ oxygen carriers by ultrasonic method and their performance in chemical looping combustion

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• 作者：Xing Chen ; Shuai Zhang ; Rui Xiao and Peng Li
• 刊名：Greenhouse Gases: Science and Technology
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：7
• 期：1
• 页码：65-77
• 全文大小：2370K
• ISSN：2152-3878

文摘

The selection of high-performance oxygen carriers has always been a major focus of attention and considered to be a determining factor in chemical-looping combustion (CLC). The traditional impregnation method by agitator for material synthesis usually causes a long crystallization time, uncontrollable crystalline size formation, and insufficient penetration and dispersion of the active component into the binder. The physical incorporation of ultrasound technology into the impregnation process is considered an effective method in the material synthesis field. In this study, the modification of a traditionally impregnated Fe₂O₃/Al₂O₃ oxygen carrier by ultrasonic method and its performance in the CLC process with methane as fuel were investigated to clarify the ultrasonic effect on the physicochemical properties of the Fe₂O₃/Al₂O₃ oxygen carrier. The characterization and optimization of an ultrasonic-assisted Fe₂O₃/Al₂O₃ oxygen carrier by varying the ultrasonic time and ultrasonic power were especially in focus. The results confirmed a significant improvement in the physical properties of the Fe₂O₃/Al₂O₃ oxygen carrier and its reactivity performance by ultrasonic modification. Ultrasound effectively promoted the penetration and dispersion of Fe₂O₃ into the pores and on the surface of Al₂O₃ powder, resulting in a great reduction in crystalline size. Higher methane conversion was obtained by an ultrasonic-assisted Fe₂O₃/Al₂O₃ oxygen carrier. The optimal ultrasonic parameters determined by orthogonal experimental design (OED) method and characterization analyses were 30 min of ultrasonic time and 500 W of ultrasonic power. Cyclic tests showed that the CO₂ yield and CH₄ conversion increased slightly from around 28% to 34% and 70% to 76%, respectively. Characterization indicated that the pore structural properties of reduced UI-20Fe/Al-30-300 samples were improved at typical cycles, resulting in more CH₄ converted. Overall, ultrasound technology is a promising way to promote the physicochemical properties of oxygen carriers in the CLC process.