An Integrated Absorption–Mineralization Process for CO2 Capture and Sequestration: Reaction Mechanism, Recycling Stability, and Energy Evaluation

An integrated absorption–mineralization process (IAM) was proposed to desorb and mineralize CO2 captured by amine solvents using the semidry desulfurization slag (DFS). Four typical amine solvents (monoethanolamine, diethanolamine, methyl-diethanolamine, and 2-amine-2-methyl-1-propanol) were investigated in the IAM process to evaluate the working capacity, recycling stability, and regeneration ability of the amine solvents. The reaction mechanism between CO2-saturated amine solutions and the DFS was interpreted with characterization by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The results indicated that bicarbonates were more beneficial to CO2 chemical desorption than carbamates. Calcium hydroxide could mineralize bicarbonate and regenerate protonated amines, while calcium sulfate could only desorb bicarbonates and carbamates. By adjusting the solid–liquid ratio to prevent calcium from participating in mineralization, 2-amine-2-methyl-1-propanol showed the best recycling performance among all the amines because of its fast absorption rate, high CO2 desorption efficiency, and excellent stability.