Hydrogen production by coal direct chemical looping (CDCL) process with iron-based oxygen carrier is an attractive option to produce H₂ with sequestration-ready CO₂. However, low reduction rate and high endothermicity are the two main difficulties of this process. In this work, the reduction rate of K-Fe-Al composite oxygen carrier by coal char, and the effect of Al₂O₃ on the endothermic property and sintering of oxygen carrier during reduction were investigated by thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), X-ray diffractometer (XRD), and scanning electron microscopy (SEM). The feasibility of this process was preliminary analyzed using a fixed-bed reactor by simulating different reaction steps. It was found that the reduction rate of composite oxygen carrier increased remarkably with higher potassium amount, but decreased with increasing Al₂O₃ amount. However, the addition of Al₂O₃ into oxygen carrier could not only mitigate the sintering, but also alleviated the endothermicity of reduction by the exothermic formation of FeAl₂O₄. This preliminary feasibility analysis suggests that it is possible to produce H₂ using CDCL with the K-Fe-Al composite oxygen carrier

用铁基氧气载体通过煤直接化学循环（CDCL）工艺生产氢是采用随时可封存的CO ₂生产H _2的一种有吸引力的选择。然而，低还原率和高吸热性是该过程的两个主要困难。本文研究了煤焦还原K-Fe-Al复合氧载体的过程以及Al ₂ O ₃的作用。用热重分析仪（TGA），差示扫描量热法（DSC），X射线衍射仪（XRD）和扫描电子显微镜（SEM）研究了还原过程中氧载体的吸热性能和烧结。通过模拟不同的反应步骤，使用固定床反应器初步分析了该方法的可行性。结果表明，复合氧载体的还原速率随钾含量的增加而显着增加，而随Al ₂ O ₃含量的增加而降低。但是，在氧气载体中添加Al ₂ O ₃不仅可以减轻烧结，还可以通过放热形成FeAl ₂ O减轻还原的吸热性。₄。初步的可行性分析表明，使用CDCL和K-Fe-Al复合氧载体可以生产H ₂