Abstract: Fe-based oxygen carrier is regarded as a promising industrial oxygen carrier,but there are some problems of low oxygen utilization rate and easy sintering at high temperatures.Although the performance of Fe-based oxygen carriers can be improved by preparing bimetallic composite oxygen carriers or adding inert components,there are certain defects.If the active components and inert materials can be integrated into a crystal structure to prepare oxygen carrier with spinel structure,the synergistic effect of bimetal can be used to improve the activity performance of oxygen carrier while Al~(3+) is employed to improve the stability of oxygen carrier.The NiFeAlO_4 oxygen carrier with spinel structure were synthesized via co-precipitation method and sol-gel method.The effects of preparation method and mass ratio(oxygen carrier to coal) on the coal chemical looping combustion reaction and cycling stability of the NiFeAlO_4 oxygen carrier were experimentally investigated.The function of oxygen carrier in coal conversion was also studied.The results show that NiFeAlO_4 oxygen carrier synthesized by sol-gel method possesses superior reactivity.When the mass ratio between oxygen carrier and coal was 20∶1,the carbon conversion is 86.7%,which is higher than that of coal pyrolysis(34%),and the CO_2 relative concentration is 93.6%.The analysis of the crystal structure and morphology of NiFeAlO_4 oxygen carrier before and after the reaction shows that the Ni O detected after 10th redox cycle and the grain agglomeration are the main reason for the decrease of its cyclic stability.Compared to its heating supply function,NiFeAlO_4 oxygen carrier mainly plays the role of oxygen supply in coal chemical looping combustion,which not only promotes the conversion of volatile matter to coal gas,but also has solid-solid reaction between NiFeAlO_4 oxygen carrier and coke,and is conducive to the generation of more CO_2.