Synergistic promoting of CO₂ absorption-mineralization by MEA-carbide slag

Thermal amine regeneration CO2 capture with amines is the most widely used technology. However, this method suffers from high energy consumption and amine losses, and captured CO2 storage safety limits its further application. To achieve CO2 capture and utilization with low energy consumption and high efficiency, this study constructed a CO2 synergistic absorption-mineralization reaction system based on monoethanolamine (MEA)-carbide slag (CS). The CO2 capture process and its effects are analyzed. The circulating absorption-mineralization activity of the coal-fired flue gas of the MEA-CS is studied. Compared with other technologies, it has good CO2 coupled absorption-mineralization performance for coal-fired flue gas and promotes the green utilization of CS and produces high-value CaCO3 products. CS can promote MEA recycling, which determines the CO2 absorption. MEA determines the CO2 absorption-mineralization rate; however, the CO2 absorption-mineralization rate does not change when MEA is > 0.1 mol/L. MEA has the best synergistic effect with CS compared to the other amines. After five rounds of experiments, the CO2 capture efficiency of MEA-CS decreases by approximately 3 %. MEA loss leads to a decrease in the CO2 capture efficiency, which includes physical and chemical losses. The main loss of MEA is the physical loss, which can be reduced by low MEA concentrations. The CO2 absorption-mineralization product is CaCO3. Compared with other CO2 capture technologies, the regeneration energy consumption is lower, and the existence of captured CO2 in solid form avoids the problem of CO2 storage and utilization.