“The stability of Ni/CeO2-CaO bifunctional combined material was presented by carrying out 20 cycles of ICCU-RWGS at 650 °C (Fig. 9). The Ni/CeO2-CaO possessed a < 5% decrease for CO and C1 yield (CO2 + CO + CH4) and > 99% CO selectivity after 20 cycles, indicating the excellent and stable ICCU-RWGS performance. Notably, the overall CO2 conversion slightly increased from 56.07% in the 1st cycle to 62.03% in the 20th cycle, which outperforms the state-of-art ICCU-RWGS performance using similar conditions (Table 2). It is believed that the effective reactant spillover onto catalytic sites is critical in the catalytic process [51]. As shown in Fig. 6e, Ni/CeO2 and CaO exhibited closer contact in spent Ni/CeO2-CaO, indicating a shorter CO2 spillover distance. The self-optimisation of Ni/CeO2-CaO bifunctional combined material in ICCU-RWGS might be attributed to the volume expansion–shrinkage effect of the sol–gel CaO in cyclic carbonation-hydrogenation, which partially embedded Ni/CeO2 onto the surface layer of CaO.” https://doi.org/10.1016/j.seppur.2022.121604
“Fig. 9. Cycle performance of Ni/CeO2-CaO over ICCU-RWGS at 650 °C.” https://doi.org/10.1016/j.seppur.2022.121604
“Fig. 6. SEM images of (a) fresh sol–gel CaO; (b) and (d) fresh Ni/CeO2-CaO; (f) spent Ni/CeO2-CaO; and TEM images of (c) fresh Ni/CeO2-CaO and (e) spent Ni/CeO2-CaO.” https://doi.org/10.1016/j.seppur.2022.121604