Integrated CO₂ capture and reduction (CCR) using dual-function materials (DFMs) has emerged as a promising strategy for effective utilization of CO₂. A thorough understanding of the reaction mechanisms of CCR using the DFMs is important for enhancing their performances. In this study, Na/Al₂O₃ and Na/Cu/Al₂O₃ were compared to investigate the role of Na-based DFMs, particularly transition-metal-free DFMs, in facilitating CCR to CO. Fixed-bed experiments comprising of CO₂ capture and reduction phase were performed to examine their performances at various temperatures. The two DFMs exhibited similar behaviors during the CO₂ capture phase. In the subsequent reduction phase, the DFMs produced nearly equal amounts of CO, reaching 0.21 mmol/g, at temperatures exceeding 450 °C. By increasing the temperature to 500 °C, the CO production rates reached an identical level of 0.18 mmol/(min·g). Time-resolved in-situ spectroscopy confirmed the formation of carbonate species during the capture phase. Carbonates were further reduced to CO directly or via intermediate formate species in the reduction phase. The formation of formates was predominant on Na/Cu/Al₂O₃ at temperatures below 400 °C. However, at higher temperatures, the direct reductive decomposition of carbonates to form CO became the dominant pathway for both the DFMs. Elucidation of a more detailed mechanism of the direct reductive decomposition pathway is critical, particularly the role of Na sites during the reduction phase.

Recently, carbon capture and reduction (CCR) technology has gained interest to directly convert CO₂ to value-added products without requiring purification of CO₂ and its subsequent transportation. CCR to methanol in one dual function material (DFM) poses mechanistic and kinetic challenges. To counteract this, a process combining Na/Al₂O₃ as a capture component and Cu/ZnO/Al₂O₃ (CZA) as methanol synthesis catalyst was developed to allow CCR to methanol. With a 5 vol% CO₂ flow for capture and subsequent H₂ stream combined with a temperature swing, a methanol selectivity of 26 % was achieved at 9 bar. Further investigation found that Na/Al₂O₃ significantly increased methanol yield, while a stacked configuration of Na/Al₂O₃ followed by CZA significantly outperformed a mixed configuration of the two catalysts. With further investigation of operation at higher pressure and surface mechanism, an effective CCR to methanol process using two affordable yet readily available catalysts can be realized.