The formation of carbon deposition causes the oxygen carrier (OC) to not fully contact with the fuel, and the attrition causes the loss of oxygen carriers, which seriously disturb the normal operation of chemical looping combustion (CLC). Cyclic combustion efficiency of oxygen carriers is closely related to the cost of CLC technology, and it is an important part of its near commercialization. The basic concepts, devices, reaction conditions, fuel composition and reaction process of CLC were introduced in this work. Two major problems in current CLC research were analyzed and summarized. The main contents included that: (1) prolonging the cycle life cycle of oxygen carriers providing combustion oxygen demand, (2) under the optimum reaction conditions, the mechanism of carbon deposition and the measures to solve the oxygen loss caused by carbon deposition were analyzed. Firstly, the oxygen carrier?s selection, preparation methods and characteristics briefly were introduced. Different oxygen carriers had their own advantages and disadvantages, it should select suitable oxygen carriers for different fuels. The attrition analysis of oxygen carriers point was carried out. Analysts believed that with industrial significance a way to select qualified oxygen carriers materials based on attrition resistance. Secondly, the reaction mechanism of polycyclic aromatic hydrocarbons (PAHs) and the precursor of carbon black deposit were analyzed in detail by analyzing the detailed reaction in the whole process of CLC. It was concluded that the carbon deposit was mainly caused by the reaction of hydrocarbons pyrolyzed by fuel with oxygen carriers and Boudouard reaction. The corresponding solutions for different types of carbon deposit were proposed. Among them, the combination of steam injection and carbon dioxide reflux injection was promising. On this basis, the potential research needs in this field were also discussed. To improve the cycle period of oxygen carriers and restrain carbon deposition, future research should focus on the characterization and reactivity of carbon deposition on the surface of oxygen carriers, the cyclic growth model of oxygen carriers under optimal combustion conditions and the reaction mechanism of particles, as well as the exploration of new technologies for coupling removal of carbon deposition.
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