Spatial migration of lattice oxygen for copper-iron based oxygen carriers in chemical looping combustion

Oxygen carrier (OC) is of great importance in chemical looping combustion (CLC) technology. The migration rate of bulk lattice oxygen during reduction process is detrimental in reaction rate. However, the migration path of lattice oxygen is still not clear. In this study, a thermogravimetric analyzer (TGA) was used to investigate the reaction characteristics and kinetic parameters of the OC. The oxygen migration paths of CuO and CuFe 2 O 4 bulk lattices were studied by density functional theory (DFT) in a five-layer (2 × 1) CuO (1 1 1) and nine-layer (1 × 1) CuFe 2 O 4 (1 0 0) plane model. The kinetic parameters, activation energy changes and relative kinetic model of the OC reduction were explored. According to the DFT results, the deeper bulk phase oxygen requires greater more energy toovercome energy barrier for migration. CuO has a lower oxygen release capacity than CuFe 2 O 4 in the early stages, but higher in the later stage. The reaction kinetics study revealed that the reaction mechanism of the reduction of the copper-iron composite OC is a tertiary chemical reaction control mechanism. During the reaction, the activation energy of the OC changes continuously. The macroscopic reaction kinetics agree with the microscopic simulation, proving the simulation model's validity.