Both sorbent regeneration and dry reforming methane are endothermic reactions. Therefore, a higher temperature would promote both reactions for sorbent regeneration and syngas production. However, in ICCU, the source of CO2 for utilisation is from the solid phase. Thus, the capacity of the dual functional materials for CO2 capture significantly affects the overall performance of ICCU, such as syngas yield and H2/CO ratio. The reaction of CO2 capture is an exothermic reaction. Thus too high reaction temperature will not benefit carbon capture, and could result in a low capacity of CO2 capture. However, if carbon capture and sorbent regeneration (CO2 utilisation) are carried out at different temperatures. The situation will be different.
The following content about the influence of reaction temperature on ICCU-DRM is from this reference (https://doi.org/10.1016/j.ccst.2022.100052).
“It has been observed that the CH4 conversion increased with the increase of reaction temperature, while the selectivity of CO showed an opposite trend due to the side reactions like CH4 decomposition (coking) (Molina-Ramírez et al., 2020). A higher temperature in the system is a benefit for the ICCC-DRM reaction in kinetics; however, it results in the reduction of the CO2 uptake capacity at equilibrium, and promotion of side reactions such as RWGS and CH4 cracking, which affects the ratio of H2/CO in the outlet syngas and even destroy the catalytic sites in the DFMs.”
“Thus far, almost all the sorbents used in the ICCC-DRM process are high-temperature CO2 sorbents, like CaO, SrO, BaO, and Li4SiO4. However, the optimum reaction temperature for the different ICCC-DRM systems may be different. SrO-based sorbents are always operated at super high temperature windows (1100−1400 °C); however, Gu et al. (Gu et al., 2022) reported that the SrO-based DFMs could be operated at 875 °C for the reason that the double replacement of Ni and Ce altered the phase structure of SrO, which not only adjusted the carbonation/decarbonation thermodynamics to facilitate SrCO3 decomposition at relatively low temperatures but also inhibited sintering of the DFMs”
“Molina-Ramírez et al. (Molina-Ramírez et al., 2020) investigated the effect of reaction temperature from 600 to 700 °C on the ICCC-DRM performance using BaO-based DFMs. They observed that 600 °C was the best reaction temperature for the BaO-based DFMs in the ICCC-DRM system”
“The CaO-based DFMs have been explored for the ICCC-DRM process at various temperatures, like 600 °C (Cruz-Hernández et al., 2017), 650 °C (Jo et al., 2022b), and 720 °C (Hu et al., 2021b; Kim et al., 2018). After comparison, Jo et al. (Jo et al., 2022b) reported that the Ni/CaO DFMs presented a relatively stable CH4 conversion rate for the reason that the Boudouard reaction is unfavorable when the temperature is above 700 °C. However, the amount of CO generated from DFM at 700 °C was relatively low due to the low CO2 capture capacity of the DFMs. Recently, Lv et al. (Lv et al., 2021) explored the effect of reaction temperature from 600 to 650 °C on the ICCC-DRM performance using Li4SiO4-based DFMs, and reported that 625 °C was the optimum reaction temperature for the Li4SiO4-based DFMs in the ICCC-DRM system, as shown in Fig. 8.”
Fig. 8. Effect of reaction temperatures on the ICCC-DRM performance using Li4SiO4-based DFMs: (a) 625°C; (b) 600°C; (c) 650°C (Lv et al., 2021).