Performance tests under industrially relevant conditions

The following content is copied from this reference (https://doi.org/10.1016/j.ccst.2022.100052):

“Dynamic operations are necessary for the ICCC process to realize the continuous CO₂ capture and conversion, either switching different gas streams or transporting the DFMs between two (or even more) reactors (Bobadilla et al., 2016; Li et al., 2022; Wang, G. et al., 2022). Therefore, the continuous operation close to practical conditions should also be considered in further studies. Besides, reaction conditions used in the capture and conversion stages significantly affect the ICCC performance. For the CO₂ capture stage, the compositions of the CO₂-contained flue gases are highly dependent on the flue gas sources (He et al., 2022). As shown in Table 5, the CO₂ concentration differs a lot from the variation of the CO₂ source. The wide range of CO₂ concentrations in the CO₂ capture stage poses a big challenge for the DFMs. At the same time, the contaminants in the flue gas also have an influence on the DFMs. For instance, when the CO₂ capture stage was conducted under an atmosphere of 7.5% CO₂/4.5%O₂/15%H₂O/N₂ balance, the subsequent methanation reaction did not take place over the 10% Ni supported on 6.2% Na₂O/Al₂O₃ (Arellano-Treviño et al., 2019a). This was because metallic Ni was oxidized in the capture stage, which could not be reduced back under a reducing atmosphere at a temperature of 320 °C. Besides, contaminants such as O₂, SO_x, and NO_x are present in the flue gas, as shown in Table 5. They are very likely to affect the sorbent and/or catalytic components in the DFMs (e.g., formation of CaSO₄ by the reaction between CaO and SO_x), which should also be considered for the ICCC process. Turning to the CO₂ conversion stage, H₂ is commonly used to convert CO₂ to value-added products. However, note that N₂-diluted H₂, instead of pure H₂, was used in this stage in some work, which is not the case in industrial situations. Therefore, when assessing the CO₂ capture and conversion performance of the DFMs, it is of practical significance to use industrial relevant reaction conditions. Additionally, more work should be performed to explore the reaction mechanisms of the ICCC processes under industrial relevant reaction conditions, which provides theoretical guidance for the design of the DFMs.”