Synergistic stabilization of red mud-modified CaO-based dual-functional materials for integrated CO₂ Capture and RWGS Conversion under Simulated Flue Gas Conditions

Integrated CO₂ capture and utilization requires dual-functional materials (DFMs) that remain stable under flue-gas-relevant conditions. Red mud (RM), an Fe- and Al-rich industrial waste, was used with Al to modify CaO for cyclic CO₂ capture and H₂-assisted RWGS conversion. After 20 cycles, CaO/Al/RM retained 64.6% of its initial CO₂ capture capacity, compared with 47.9% for AcCaO, while the CO-yield decline was reduced from 58.1% to 34.8%. The modified material maintained a CO yield of 5.80 mmol·g⁻¹ and a CO₂ conversion of approximately 80%. RM-derived Al-containing phases contributed to structural stabilization, whereas redox-active FeO_x species promoted CO₂ conversion during H₂-assisted regeneration. Under 15% H₂O, the initial capture capacity increased by approximately 5%, and the capacity decay decreased from 35% to 17%. Under 6% CO₂, the material retained CO₂ capture and CO yields of 7.3 and 6.2 mmol·g⁻¹, respectively, after 20 cycles. The study is expected to provide reference and technical support for the preparation of low-cost DFM and the practical application of ICCU in power plants.