Ni/CeO2 promoted Ni/CaO dual functional materials for ICCU-RWGS

“With a RWGS catalyst at a relatively higher temperature, H₂ reduction of the carbonated DFMs can also produce CO rather than CH₄ (Sun et al., 2019; Wang, G. et al., 2022). For example, a sol-gel combustion method was used to synthesize CaNi_0.1 with the modification of Ce (Sun et al., 2019). The carbon capture and subsequent RWGS were operated at 650−700°C isothermally. The CaNi_0.1Ce_0.033 showed optimum performance at 650°C with the CO₂ conversion of 51.8% and CO yield of 7.3 mmol/g-DFM (∼100% selectivity). Cyclic performance tests showed an obvious decay of carbonation-conversion over 20 cycles for CaNi_0.1, mainly attributed to the agglomeration and sintering of CaO. For CaNi_0.1Ce_0.033, the performance kept unchanged after 20 cycles, demonstrating much better stability due to CeO₂ modification. Two benefits were proposed for CeO₂ modification: one was that the oxygen vacancies in CeO₂ could reduce the dissociated CO₂ released from the DFMs, facilitating the CO yield; the other was that the well-dispersed CeO₂ could act as a physical barrier to prevent the growth and agglomeration of CaO and Ni particles. Compared to the conventional RWGS reaction (CO₂ and H₂ co-feeding), the performance of the ICCC-RWGS process exhibits a higher CO₂ conversion, a more remarkable CO selectivity, and a better stability.”

https://doi.org/10.1016/j.ccst.2022.100052

The promiting effect of CeO2 regarding the stability of DFMs is shown in the following figure. It is suggested that CeO2 enhanced the dispersion of Ni on CaO and inhibited the sintering of CaO during the cycles of ICCU-RWGS.

Figure results – Cyclic CO₂ capture and conversion reactions of (a) Ca₁Ni_0.1; (b) Ca₁Ni_0.1Ce_0.033 (https://doi.org/10.1016/j.apcatb.2018.11.040)