Enhancement technologies of ammonia-based carbon capture: A review of developments and challenges

Aqueous ammonia is one of the most promising solvents to conventional amine for capturing CO₂ from flue gas and other industrial emissions owing to its high CO₂ loading capacity, low-cost, less corrosive, and low vulnerability to degradation. However, due to the slow absorption rate of CO₂, the industrial application of ammonia is restricted. The present review mainly focused on the current developments of the aqueous ammonia-based carbon capture process (AAP) and its enhancement technologies to improve the absorption rate performance. The reaction between aqueous ammonia and CO₂, including reaction mechanism, reaction intermediates, reaction products, and influence of different operational parameters on the absorption performance, are presented. The enhancement technologies, mass transfer coefficients, and perspectives for each potential technology in AAP are reviewed. Furthermore, the recent advances in the potential of ammonia for combined removal of several flue gas components such as; NO_x, SO_x, CO₂, and other pollutants are discussed. Finally, in light of recent advancements and obstacles of AAP, this study provides views and highlights in which future prospective investigation is necessary to improve the absorption rate of aqueous ammonia.