A novel thermochemical dual-membrane reactor is considered with the goal of efficiently converting CO₂ to fuels using concentrated solar energy as the process heat source. In contrast to the temperature-swing redox cycle, in this isothermal system the thermolysis of H₂O at above 1,800 K is assisted by removal of O₂ across an oxygen-permeable membrane and of H₂ across a hydrogen-permeable membrane. The latter is consumed by a stream of CO₂via the reverse water-gas shift reaction to re-form H₂O and continuously generate CO. The net reaction is the splitting of CO₂ to CO and 12O2. Because reactions at such high temperature are expected to be thermodynamically controlled, thermodynamic models are developed to calculate the equilibrium limits of the proposed dual-membrane configuration. For comparison, two reference configurations comprising either a single oxygen-permeable membrane or a single hydrogen-permeable membrane are analyzed. At 1,800 K, 1 bar total pressure, and (not applicable for the hydrogen-membrane reactor) 10 Pa O₂, the equilibrium mole fraction of fuel is 2% with a single oxygen membrane, 4% with a single hydrogen membrane, and 15% in the dual-membrane system. In all cases, total selectivity of CO₂ to CO and O₂ is obtained. Assuming thermodynamic equilibrium, the solar-to-fuel energy efficiency realistically attainable is 4% with a single oxygen membrane, 8% with a single hydrogen membrane, and 17% in the dual-membrane configuration at the aforementioned conditions. By increasing the pressure of the feed of steam to 100 bar, the dual-membrane model system could theoretically approach full mass conversion of CO₂ and reach up to 26% solar-to-fuel energy efficiency. However, developing appropriate and stable ceramic materials for such a system poses a significant challenge.

考虑到一种新颖的热化学双膜反应器，其目标是使用集中的太阳能作为过程热源将CO ₂有效地转化为燃料。与温度波动的氧化还原循环相反，在该等温系统中，H ₂ O在1,800 K以上的热分解是通过跨透氧膜的O ₂和跨透氢膜的H ₂的去除而实现的。后者被一股CO ₂流消耗通过逆水煤气变换反应重新形成H ₂ O并连续生成CO。净反应是将CO ₂分解为CO和1个2Ø2。由于预计在这种高温下的反应是热力学控制的，因此开发了热力学模型以计算所提出的双膜构型的平衡极限。为了比较，分析了包括单个透氧膜或单个透氢膜的两个参考构型。在1,800 K，总压力为1 bar，并且（不适用于氢膜反应器）10 Pa O _{2的情况下}，单个氧气膜的燃料平衡摩尔分数为2％，单个氢气膜的燃料平衡摩尔分数为4％，而15在双膜系统中的百分比。在所有情况下，CO ₂对CO和O _2的总选择性获得。假设热力学平衡，在上述条件下，单层氧气膜实际可获得的太阳能燃料效率为4％，单层氢气膜为8％，在双膜构型下为17％。通过将蒸汽进料的压力提高到100 bar，该双膜模型系统理论上可以达到CO _2的完全质量转化，并达到26％的太阳能转化为燃料的能效。然而，为这种系统开发合适且稳定的陶瓷材料提出了巨大的挑战。