Fluidized isothermal CO2 capture and in-situ syngas production in a single reactor using limestone alone
Iwei Wang, Shihui Wang, Jinzhi Cai, Jiaye Li, Qi Sun, Yongjia Yang, Zhenshan Li
Abstract
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.