Redox Reaction Kinetics of a Fe-Cu-Based Oxygen Carrier Measured with Microfluidized Bed Thermogravimetric Analysis

摘要

The redox kinetics of a Fe-Cu-based oxygen carrier at 450-600 ℃ was measured under the fluidization state just like an actual chemical looping combustor, using a microfluidized bed thermogravimetric analysis technology. The oxidation and reduction reaction processes were described by a product-island-based rate equation theory, and the complex physical/chemical steps during the chemical reactions were considered in the model, including the interphase mass transfer in bubbling bed reactor, external particle diffusion, intraparticle diffusion, surface reaction, product island growth, etc. The prediction accuracy of the developed theory was validated by the experimental data, and the kinetic parameters were obtained. For the reduction reaction, it was found that the Fe-Cu-based oxygen carrier can be completely reduced within 30 s by 10 vol % H_2. For the oxidation reaction, its kinetics vs time curves exhibited obvious two-stage characteristics, and the first stage of the oxidation reaction with 21 vol % O_2 was ultrafast and can reach a conversion level of 60% within 3 s. Moreover, the controlling mechanisms between mass transfer and chemical reaction during the oxidation and reduction reaction were analyzed.