Steel production using coal accounts for ∼ 8% of global carbon emissions. “Green Steel” is a new grand concept proposed recently to make steel from iron ores using renewable derived “Green Hydrogen” to achieve zero carbon emission. The kinetics and rate-limiting steps of iron ore reduction into iron with H₂ as a reducing agent is critically important to the success of this new technology. While reduction of Fe₂O₃ into Fe by H₂ follows multiple steps, the past research on this topic mainly deals with the overall averaged kinetics, giving little information on the elemental and rate-limiting steps. Here we report a kinetic study specifically design to attain kinetic rate constants of one-step reduction of Fe₃O₄-to-Fe and FeO-to-Fe. Guided by thermodynamics, we show first how to create in situ the desirable starting oxide phases, i.e., Fe₃O₄ and FeO, with precisely controlled the ratio of partial pressures of H₂O and H₂. We then show time-dependent raw H₂O content data collected by a mass spectrometer and the processed reduction data to extract kinetic rate constants. We found that the kinetics of the two one-step reduction reactions follows nicely the Johnson-Mehl-Avrami (JMA) phase transformation model. The one-step reduction mechanisms and activation energy are also discussed.

使用煤炭的钢铁生产占全球碳排放量的 8%。“绿色钢铁”是最近提出的一个新的宏大概念，即利用可再生衍生的“绿色氢”以铁矿石炼钢，实现零碳排放。_{以H 2}作为还原剂将铁矿石还原成铁的动力学和限速步骤对于这项新技术的成功至关重要。虽然通过 H _{2将 Fe 2} O ₃还原为 Fe遵循多个步骤，但过去对该主题的研究主要涉及整体平均动力学，很少提供有关元素和限速步骤的信息。_{在这里，我们报告了一项动力学研究，专门设计用于实现 Fe 3} O一步还原的动力学速率常数₄ -to-Fe 和 FeO-to-Fe。在热力学的指导下，我们首先展示了如何在精确控制 H ₂ O 和 H ₂分压比的情况下原位生成理想的起始氧化物相，即 Fe ₃ O ₄和 FeO 。然后，我们显示由质谱仪收集的与时间相关的原始 H ₂ O 含量数据和处理后的还原数据以提取动力学速率常数。我们发现两个一步还原反应的动力学很好地遵循 Johnson-Mehl-Avrami (JMA) 相变模型。还讨论了一步还原机制和活化能。