Kai Shi, Jie Gao, Jingyu Ran, Xin Huang, Yunlin Shao, Chuan Ma
Reverse water-gas shift chemical looping (RWGS-CL) process is a highly attractive thermochemical CO 2 utilization technology, yet oxygen carriers often suffer from insufficient low-temperature oxygen mobility and deactivation by high-temperature sintering. This study systematically examined the role of porous silica-based frameworks (ZSM-5, SBA-15, and SiO 2 aerogel) in modulating the redox activity and stability of CoFe 2 O 4 during RWGS-CL. The results showed that ZSM-5 with abundant microporous structure exhibited the most significant promotion of CoFe 2 O 4 reducibility and oxygen vacancy formation, enhancing CO 2 -splitting activity. CoFe 2 O 4 supported on 30 wt% ZSM-5 (CZ30) delivered the optimal performance, achieving CO yields of 13.8 and 11.4 mmol·g CoFe −1 in the first and fifth cycles at 650 °C, respectively. However, Co segregation during redox cycling gradually reduced its activity. To overcome this limitation, an O 2 -assisted strategy was introduced to ensure the complete re-oxidation of the CoFe alloy, facilitating the redox reversibility of the oxygen carriers. Under O 2 -assisted conditions, the CZ30 catalyst maintained a CO yield of approximately 12.8 mmol·g CoFe −1 over ten cycles, outperforming most reported supported iron-based and spinel oxygen carriers and demonstrating enhanced redox stability. These findings highlight that the textural characteristics of the support critically govern redox activity and stability of oxygen carrier, and further establish CoFe 2 O 4 /ZSM-5 as an effective material for CO 2 -splitting via RWGS-CL.