第二届中国化学链会议

The oxygen release ability of oxygen carrier is an important evaluation index of chemical looping combustion. Spinel CuCo₂O₄ is a kind of oxygen carrier which cooperates with the magnetism of Co₂O₃ oxygen carrier and the strong oxygen release ability of CuO. It has excellent characteristics of high oxygen release, recyclability and anti-sintering ability. Based on experiments and density functional theory (DFT) calculations, the oxygen release ability and mechanism of CuCo₂O₄ oxygen carrier were studied. Thermogravimetric analyses (TGA) showed that the oxygen release temperature of CuCo₂O₄ is lower than that of Co₃O₄ and CuO. CuCo₂O₄ has stronger oxygen release ability. The simulation results show that the oxygen migration energy is 55 kJ/mol, which is much lower than that of Co₃O₄. O₂ tends to adsorb vertically on the top of Cu in CuCo₂O₄ to form chemisorbed oxygen, which has higher adsorption energy than Co²⁺ in Co₃O_4. The desorption energy of chemically adsorbed oxygen is lower than that of lattice oxygen. Oxygen release in chemical looping combustion can be divided into three processes: desorption of chemisorbed oxygen, formation of oxygen vacancies by surface oxygen desorption, and migration of lattice oxygen to surface oxygen vacancies.
 

CuCo2O4; oxygen release; chemical looping combustion