Mo/Fe–CaO Dual-Functional Materials for the Integrated CO₂ Capture and Reverse Water–Gas Shift

Integrated CO2 capture and conversion (ICCC), which simultaneously achieves CO2 enrichment and in situ conversion, represents a promising strategy for reducing CO2 emissions. Dual-function materials (DFMs) that exhibit stable and highly efficient adsorption and catalytic conversion properties are essential to the success of this strategy. In this study, we developed novel Mo/Fe-doped CaO-based DFMs for the integrated CO2 capture and reverse water–gas shift (ICCC–RWGS) process. The synthesized DFMs was evaluated through adsorption–conversion cyclic experiments in a fixed-bed reactor, complemented by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) mapping, and X-ray photoelectron spectroscopy (XPS) characterizations. The results indicate that the generated composites with a specialized structure not only provide stable support for CaO but also regulate the RWGS process. Specifically, the formation of Ca2Fe2O5 facilitates the hydrogenation of CaCO3 via redox reactions, while the generation of CaMoO4 and Ca2FeMoO6 alleviates both the volume-change effects of CaO caused by CO2 adsorption–hydrogenation cycles and the carbon deposition side reactions caused by Fe. DFMs with a Mo/Fe mass ratio of 1:9 exhibited a CO2 capture capacity of 14.8 mmol/g DFM, a CO yield of 11.4 mmol/g DFM, and good cyclic properties at 650 °C, making it a promising DFM for ICCC–RWGS. In conclusion, the utilization of superstructures with superior redox reactivity and structural stability, such as perovskite and spinel, offers valuable insights into the design of DFMs for ICCC.