Fe-Ni oxygen carrier particles for mid-temperature natural gas chemical looping reforming: Mechanism and large-scale performance

Hydrogen production is crucial for supporting the energy transition and achieving carbon neutrality goals. However, conventional natural gas steam reforming suffers from high temperatures, which lead to substantial exergy losses, promote carbon deposition, and compromise operational stability. Here, a mid-temperature (500–600 °C) chemical looping steam reforming (CLSR) process is proposed for efficient natural gas conversion. Fe Ni oxygen carrier particles were developed by varying Fe/Al precursors, calcination temperatures, and powder sizes to achieve modulated physico-chemical properties. Systematic evaluation of chemical reactivity and physical indicators identified nm-Fe 2 O 3 -γ-Al 2 O 3 calcined at 1200 °C as the optimal formulation, combining high reactivity with a mechanical strength of 55.3 N. Reaction behavior was further investigated in a bench-scale packed-bed reactor with 100 g oxygen carrier loading. At 600 °C and a steam-to‑carbon ratio of 1.5, the optimized process achieved over 85 % natural gas conversion and nearly 100 % ethane conversion, yielding a hydrogen production of 25 mL g OC −1 and an H 2 /CO ratio of 1.8. In addition, long-term stability tests confirmed that the oxygen carriers retained their oxygen transfer capacity and microstructure after 1000 isothermal redox cycles, while cold attrition tests showed a mass loss of only 0.73 % over 2 h. Furthermore, in-situ DRIFTs and XRD provided clear mechanistic insights into the CLSR process over Fe Ni oxygen carriers, confirming the reaction pathway of natural gas activation and hydrogen production. Collectively, these findings highlight the promising performance of CLSR as an efficient route for low-carbon hydrogen production from natural gas.`.