The reverse water gas shift (rWGS) reaction represents an attractive route for CO₂ activation with H₂ to generate CO that can be used as an intermediate in the production of fuels and chemicals. Here, we investigate the implementation of the rWGS reaction via thermochemical redox cycling, in which the overall rWGS reaction is split up into two half reactions of reduction and oxidation of a metal/metal oxide solid material. This can be practically implemented by spatially separating the two half-reactions in a two-reactor circulating fluidized bed in which metal/metal oxide particles are continuously circulated between the two reactors and thus provide a net oxygen transport from one reactor to the other. In this context, we aim to answer the question whether it is more beneficial to exploit crystalline phase changes or oxygen non-stoichiometry in the material to transport oxygen, by process analysis based on thermodynamic data. We find that phase change materials offer a better potential process efficiency, however at the expense of an inflexible CO product purity. For all materials, a trade-off exists between process efficiency and CO product purity, and we identify a number of promising phase change materials that populate this trade-off and appear suitable to produce a high enough CO concentration for industrial methanol synthesis without any further gas purification.

反向水煤气变换（rWGS）反应代表了用H ₂活化CO ₂的诱人途径产生一氧化碳，可将其用作燃料和化学品生产的中间体。在这里，我们研究了通过热化学氧化还原循环实现rWGS反应的过程，其中整个rWGS反应分为金属/金属氧化物固体材料还原和氧化的两个半反应。这可以通过在两个反应器循环流化床中将两个半反应在空间上分开来实际实现，在该反应器中，金属/金属氧化物颗粒在两个反应器之间连续循环，从而提供从一个反应器到另一个反应器的净氧输送。在这种情况下，我们的目标是通过基于热力学数据的过程分析来回答在材料中利用结晶相变还是利用非化学计量的氧气来传输氧气是否更有益的问题。我们发现，相变材料可提供更好的潜在工艺效率，但是会牺牲一成不变的CO产品纯度。对于所有材料，在工艺效率和一氧化碳产品纯度之间都需要权衡取舍，我们确定了许多有前途的相变材料，这些相变材料构成了这种权衡取舍，并且似乎适合产生足够高的一氧化碳浓度用于工业甲醇合成气体净化。