In Situ Capture and Conversion of CO₂ to CO Using CaZrO₃ Promoted Fe–CaO Dual-Functional Material

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 ).