Durability and Kinetic Testing of Ni-Ceria at Elevated Pressure During Chemical Looping Dry Reforming of Methane

Chemical looping reforming of methane (CLRM) is a promising route for low-emission synthesis gas production. Current CLRM technology remains primarily at the laboratory scale where the most promising redox intermediates have been tested under relatively benign conditions, such as ambient pressure, low (<10%) CH4 concentrations and with limited cycling stability. This work investigates the stability and kinetic behavior during dry CLRM using the candidate redox intermediate Ni-ceria (Ni-CeO2), under industrially relevant conditions─i.e., 90% CH4, 90% CO2, and 5 bar pressure. Specifically, parametric experimental studies were conducted to understand the effects of residence time (tres = 6.6–26.38 s), temperature (T = 700, 800, 900 °C), and controlled bed-average oxygen nonstoichiometry ranges (δ̅ = 0–0.14) via nonsteady cycling on syngas yields and CH4 conversions. It was observed that under conditions which enabled the highest conversions (i.e., high tres) selectivity to H2 and CO were negatively impacted. We find that in intermediate conditions (tres = 13.19 s) high conversions (>98%) and selectivities (H2 > 90% and CO > 80%) can be achieved, specifically at (T = 900 °C, tres = 13.19 s, and 0.1 < δ̅ < 0.14). These identified intermediate conditions were used to demonstrate redox stability over 1000 redox cycles. Results demonstrated consistent redox cycling behavior, high methane conversion (∼0.99), and effective syngas selectivities (SH2 ∼0.91, SCO ∼0.83) at 5 bar and 90% vol of reactants. These results establish Ni-ceria as a stable, durable, and kinetically favorable redox intermediate for pressurized CLRM, combining rapid reforming rates with long-term redox stability, supporting its potential for industrial-scale in situ syngas production for applications such as Fischer–Tropsch synthesis, methanol production, and other syngas-based processes amid the ongoing energy transition.