Chemical looping syngas production is a two-step redox cycle with oxygen carriers (metal oxides) circulating between two interconnected reactors. In this paper, the performance of pure CeO₂/Ce₂O₃ redox pair was investigated for low-temperature syngas production via methane reduction together with identification of optimal ideal operating conditions. Comprehensive thermodynamic analysis for methane reduction and water and CO₂ splitting was performed through process simulation by Gibbs free energy minimization in ASPEN Plus^®. The reduction reactor was studied by varying the CH₄/CeO₂ molar ratio between 0.4 and 4 along with the temperature from 500 to 1000 °C. In the oxidation reactor, steam and carbon dioxide mixture oxidized the reduced metal back to CeO₂, while producing simultaneous streams of CO and H₂ respectively. Within the oxidation reactor, the flow and composition of the mixture gas were varied, together with reactor temperature between 500 and 1000 °C. The results indicate that the maximum CH₄ conversion in the reduction reactor is achieved between 900 and 950 °C with CH₄/CeO₂ ratio of 0.7–0.8, while, for the oxidation reactor, the optimal condition can vary between 600 and 900 °C based on the requirement of the final product output (H₂/CO). The system efficiency was around 62% for isothermal operations at 900 °C and complete redox reaction of the metal oxide.

中文翻译：

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甲烷还原和CO 2 + H 2 O氧化对非催化氧化铈生产合成气的热力学评估

化学回路合成气的生产是两步氧化还原循环，氧气载体（金属氧化物）在两个相互连接的反应器之间循环。在本文中，研究了纯CeO ₂ / Ce ₂ O ₃氧化还原对通过甲烷还原生产低温合成气的性能，并确定了最佳理想操作条件。为减少甲烷和水和二氧化碳综合热力学分析₂通过流程模拟通过最小吉布斯自由能在阿斯彭加进行分割^®。通过改变CH ₄ / CeO _2来研究还原反应器摩尔比在0.4和4之间，温度范围从500到1000°C。在氧化反应器中，蒸汽和二氧化碳混合物将还原的金属氧化回CeO ₂，同时分别产生同时的CO和H ₂物流。在氧化反应器内，混合气体的流量和组成以及反应器温度在500至1000°C之间变化。结果表明，还原反应器中的最大CH ₄转化率在900至950°C之间实现，CH ₄ / CeO ₂比为0.7–0.8，而对于氧化反应器，最佳条件可在600至900°之间变化C根据最终产品产量的要求（H ₂/ CO）。对于900°C的等温运行以及金属氧化物的完全氧化还原反应，系统效率约为62％。