Regeneration mechanism of CuO-CaSO4 based oxygen carriers

CuO-CaSO4 based materials are widely used in chemical looping technology. Although the reduction process is essential, the regeneration process of the oxygen carrier is also vital. The regeneration capacity determines the lifetime of the oxygen carrier. The exploration of the regeneration mechanism of oxygen carriers is an indispensable part of its applicability in industry. Recently, just a few reports were dealing with the regeneration of CuO-CaSO4 oxygen carriers. In the present work, the regeneration mechanism of the CuO-CaSO4 oxygen carriers was analyzed by thermodynamic, and kinetic analysis. It was observed that the high temperature is not beneficial to the occurrence of these reactions at 923 K. The CuO-CaSO4 oxygen carrier could be regenerated entirely. The regeneration process was described in two steps, with the 3D symmetry diffusion module. The first step was when CaS, Cu2S, Cu reacts with oxygen to produce CaSO4, Cu2O, CuSO4, and some CuO. The second step is the oxidation of Cu2O to generate CuO. After analysis, the regeneration kinetic function of the oxygen carrier compound of CuO-CaSO4 has been achieved. This work indicates that the CuO-CaSO4 based oxygen carrier is a recommended oxygen carrier in the chemical looping process, which lays a foundation for the practical industrial application of the oxygen carriers.