Fe2O3/Al2O3氧载体制备方法的研究

采用溶胶-凝胶法、共沉淀法、水热合成法、低热固相合成法、机械混合法、燃烧合成法和冷冻成粒法制备铁基氧载体Fe₂O₃/Al₂O₃,并通过物理和化学表征手段来筛选和优化制备方法和制备工艺。对煅烧后的氧载体进行硬度测试,结果表明,溶胶-凝胶法、共沉淀法、机械混合法、燃烧合成法和冷冻成粒法制备的氧载体硬度较高;载体的X射线衍射(XRD)谱图表明,各种制备方法均能制得物相组成为Fe₂O₃/Al₂O₃的氧载体,且随着煅烧温度的提高、煅烧时间的延长,氧载体的结晶度、晶体粒径逐渐增大,煅烧温度1 200℃的氧载体的机械性能、晶体结构、晶相组成更稳定。借助化学吸附仪的程序升温还原(TPR)实验表征氧载体的反应活性,并计算氧载体活性度。综合物理和化学表征实验结果表明,最优制备方法为溶胶-凝胶法和冷冻成粒法。

Preparation method study on Fe2O3/Al2O3 oxygen carrier

Oxygen carrier is one of the essential issues of Chemical Looping Combustion (CLC). In this paper, Fe-based oxygen carriers were prepared by the following seven methods: sol-gel method, co-precipitation method, hydrothermal synthesis method, low-heating solid-state reaction method, mechanical mixing method, combustion synthesis method, and freeze granulation method. The appropriate preparation methods were selected and optimized for preparation process through physical and chemical characterization. Firstly, the hardness tests of the oxygen carriers showed that the oxygen carriers prepared by sol-gel, co-precipitation, mechanical mixing, combustion synthesis, and freeze granulation are harder than others. Then, these oxygen carriers were tested by X-Ray Diffraction (XRD), and Fe₂O₃/Al₂O₃ crystalline phase were found in all these samples. Further XRD analysis showed that the crystallinity and crystallite size of oxygen carriers gradually increased with the increase of calcining time and temperature. The mechanical property, crystal structure and composition of crystalline phase are the most stable when the calcining temperature is 1 200℃. Finally, Temperature Programmed Reduction Reaction (TPR) experiments by the Chemisorption Instrument were carried out to characterize the reactivity of the oxygen carriers, and the activity degree of oxygen carriers was obtained. Following these physicochemical characterizations, the sol-gel method and freeze granulation method were recognized as best for the preparation of Fe₂O₃/Al₂O₃ oxygen carrier.