化学链制氢系统中磁铁矿氧载体的 CO 还原特性研究

Magnetite has the significant advantages of low cost and environmental friendliness as an oxygen carrier in chemical looping hydrogen production system. However, the controlled mechanisms of its reaction rate during CO reduction remain are not fully understood. In this study, thermogravimetric analysis was used to investigate the reaction characteristics and multi-step reaction kinetics of 20%CO isothermal reduction of magnetite under conditions ranging from 650℃ to 900℃ . The semi-quantitative analysis results indicate that the coupling relationship between the two-step reactions Fe₃O₄→FeO and FeO→Fe is temperature-dependent. In the temperature range of 650—750℃, the two-step reactions are highly overlapped, whereas in the temperature range of 800—900℃, the two steps occur in a sequential manner. Based on this, kinetic analysis was performed using the JMA model approach. The first step reaction is controlled by the chemical reaction model or three-dimensional nucleation model (Avrami-Erofe’ev model), while the second step reaction is controlled by the diffusion model.