Fluidized isothermal CO2 capture and in-situ syngas production in a single reactor using limestone alone

• A carbon–neutral pathway using thermocatalytic-induced ICCU is proposed. • CO 2 capture and utilization were studied in fluidized isothermal condition . • MFB-TGA-MS and a continuous fluidized bed system were utilized for ICCU-RWGS. • Multiscale kinetic modeling revealed CaO’s intrinsic self-catalytic activity. This study proposes an innovative, green, and carbon–neutral method for decarbonization through thermocatalytic-induced integrated CO 2 capture and utilization. Despite its promise, this approach faces significant challenges, including a limited understanding of the mechanisms involving limestone (CaCO 3 ), the potential of low-cost dual-functional materials, and the feasibility of achieving continuous CO 2 capture and syngas production under fluidized isothermal conditions. To address these challenges, this study investigated the performance of ten natural limestone samples using micro-fluidized bed thermogravimetric analysis coupled with mass spectrometry and continuous fluidized bed systems. The findings revealed 100% CO selectivity and a CO 2 conversion rate of 82.2%, driven by the intrinsic catalytic activity of calcined CaO without the need for additional catalyst composition. Furthermore, a 100-hour stability test under fluidized, isothermal conditions demonstrated no signs of deactivation. Continuous syngas production achieved a CO 2 capture efficiency exceeding 98%, with an H 2 /CO ratio of 1.0–1.5 maintained across five operational cycles. Multiscale kinetic modeling and density functional theory (DFT) calculations confirmed that the reaction proceeds via a CaO self-catalytic mechanism. These results highlight limestone’s potential as a scalable, sustainable material for syngas production and reinforce its viability in advancing carbon–neutral technologies.