In Situ Capture and Conversion of CO<sub>2</sub> to CO Using CaZrO<sub>3</sub> Promoted Fe–CaO Dual-Functional Material
Zhuxian Gao, Yongning Yuan, Panpan Yang, Xiude Hu, Jingjing Ma, Qingxiang Ma, Tuo Guo, Jianli Zhang, Qingjie Guo
Abstract
The urgent need to address global warming has led researchers to investigate various methods for capturing and utilizing CO 2 . One promising approach is the integration of calcium looping (CaL) and reverse water–gas shift (RWGS) reactions. Therefore, dual functional materials enriched with CaZrO 3 were introduced as effective catalysts, exhibiting a sustainable catalytic CO 2 conversion to 100% CO selectivity and a remarkable CO 2 adsorption capacity (16.69 mmol g DFM –1 ), CO yield (9.64 mmol g DFM –1 ), even under low hydrogen concentration (15% H 2 ) in CaL and RWGS processes. Surface chemistry analysis revealed that oxygen vacancies, acting adsorption sites, and lattice oxygen of CaZrO 3 can be activated by hydrogen. This activation, linked to the formation of strong basic sites with Zr 4+ -O 2–, significantly enhanced CO 2 conversion efficiency. The synergistic promotion mechanism was validated through in situ X-ray diffraction, DRIFTS, and Raman spectroscopy techniques. The bidentate formate mechanism was predominant, indicating that bicarbonates and hydroxyl synergistic promote CO 2 conversion in the high-temperature CaL–RWGS process. 10FCZ–5 showed good long-time stability, and the material maintained a high dispersion of Fe species after 10 cycles, demonstrating excellent absorbent capacity (11 mmol g DFM –1 ) and CO yield (6.2 mmol g DFM –1 ).