To mitigate CO₂ emissions, its reduction by high-temperature electrolysis using solid oxide cells is extensively investigated, for which excessive steam supply is assumed. However, such condition may degrade its feasibility due to massive energy required for generating hot steam, implying the needs for lowering steam demand. In this study, high-temperature electrolysis of CO₂-enriched mixtures by using fuel-electrode supported La_0.6Sr_0.4CoO₃/YSZ/Ni-YSZ solid oxide cells is considered to satisfy such needs. The effect of internal and external steam supply on its electrochemical performance and gas productivity is elucidated. It is shown that the steam produced in-situ inside the fuel-electrode by a reverse water gas shift reaction may decrease significantly the electrochemical resistance of dry CO₂-fed operations, attributed to self-sustaining positive thermo-electrochemical reaction loop. This mechanism is conspicuous at low current density, whereas it is no longer effective at high current density in which total reactant concentrations for electrolysis is critical. To overcome such limitations, a small amount of external steam supply to the CO₂-enriched feed stream may be needed, but this lowers the CO₂ conversion and CO/H₂ selectivity. Based on these results, it is discussed that there can be minimum steam supply sufficient for guaranteeing both low electrochemical resistance and high gas productivity.

为了减轻CO ₂排放，已广泛研究了通过使用固体氧化物电池的高温电解来减少CO _2的排放，并假定了过量的蒸汽供应。然而，由于产生热蒸汽所需的大量能量，这种情况可能降低其可行性，这意味着需要降低蒸汽需求。在这项研究中，CO的高温电解₂ -富集通过使用燃料极支持混合物的La _0.6锶_0.4的CoO ₃ / YSZ /镍YSZ固体氧化物电池被认为满足这样的需求。阐明了内部和外部蒸汽供应对其电化学性能和气体生产率的影响。结果表明，蒸汽原位产生逆向水煤气变换反应在燃料极内部可能会大大降低干式CO _2进料操作的耐电化学性，这归因于自我维持的正热电化学反应回路。该机制在低电流密度下很明显，而在高电流密度下不再有效，在高电流密度下，用于电解的总反应物浓度至关重要。为了克服这种局限性，外部蒸汽供应到CO的少量₂ -富集的可能需要的进料流，但是这降低了CO ₂的转化率和CO / H ₂选择性。基于这些结果，讨论了可以有最少的蒸汽供应，足以保证低的耐电化学性和高的气体生产率。