Abstract:

The CoFeAlO₄ oxygen-containing materials with spinel structure were synthesized by combustion synthesis. The chemical looping combustion reaction and cycling thermal stability of CoFeAlO₄ oxygen carriers were investigated and characterized at different temperatures. The changes in the crystal structure and surface morphology of CoFeAlO₄ oxygen carriers were analyzed. The results show that the increase of temperature is beneficial to improve the ability of CoFeAlO₄ to convert reducible gas CO, resulting in the reduction rate faster, but redox at high temperature will cause CoFeAlO₄ oxygen carrier phase separation, it is difficult to maintain a stable self-supported spinel structure. The analysis of the crystal structure of CoFeAlO₄ oxygen carrier crystals before and after the reaction shows that the CoFe₂O₄ and CoAl₂O₄ detected after the redox cycle at high temperature is the main reason for the sintering of CoFeAlO₄ oxygen carrier and the decrease of its cyclic thermal stability.

Key words: chemical looping combustion, oxygen carrier, CoFeAlO₄, self-supported function, phase change

摘要：

采用燃烧法合成了具有尖晶石结构的CoFeAlO₄载氧体材料，通过表征手段和实验研究考察了不同温度下CoFeAlO₄载氧体的化学链燃烧反应特性和循环稳定性，并对CoFeAlO₄载氧体晶相结构和表观形貌的变化规律进行了分析。结果表明，温度升高有利于提高CoFeAlO₄载氧体转化还原性气体CO的能力，使得还原反应速率更快，但高温下经“还原-氧化”会造成CoFeAlO₄载氧体相态分离，难以保持稳定的自载体尖晶石结构。对反应前后CoFeAlO₄载氧体晶相结构的分析表明，高温条件下经过“还原-氧化”后生成的CoFe₂O₄和CoAl₂O₄是导致CoFeAlO₄载氧体烧结和循环稳定性下降的主要原因。

关键词: 化学链燃烧, 载氧体, CoFeAlO₄, 自载体功能, 相态变化