Mechanistic study of integrated CO2 capture and utilization over Cu and Al-modified calcined limestone with high stability using MFB-TGA-MS

This study explores the performance of dual-functional materials (DFMs) in cyclic integrated CO2 capture and reverse water–gas shift (ICCU-RWGS) reactions under fluidized, isothermal conditions. DFMs with a copper catalyst and alumina support on calcined natural limestone were analyzed using micro-fluidized bed thermogravimetric analysis coupled with mass spectrometry (MFB-TGA-MS). The results indicate that the 10 %Cu5%Al-CaO-IMP surpasses others, demonstrating a CO2 capture capacity of 10.67 mmol⋅g−1, 71.5 % in-situ CO2 conversion at 700 °C, and remarkable cyclic stability over 30 cycles. Cu and Al additions curtail CaO agglomeration during extended ICCU-RWGS and enhance CO2 and H2 activation by removing surface formate species, promoting CO production. Furthermore, non-catalytic gas–solid reactions coexist with catalytic gas–solid reactions, leading to gradual Cu particle coating by CaCO3 during carbonation. This phenomenon prevents Cu sintering but slightly reduces catalytic activity. These findings, combined with cost-effective materials (CaO, Cu, Al), hold significant promise for efficient and economically viable ICCU processes.