Degradation of amine-based solvents in CO₂ capture process by chemical absorption

Carbon dioxide capture and storage (CCS) technologies have been proposed as a promising alternative to reduce CO₂ emissions from fossil fuel power plants with post-combustion capture. Absorption by aqueous amine-solutions is considered the most mature and industrially developed technology for post-combustion capture. One of the most significant issues hindering a large deployment of this technology is potential amine degradation. Amines degrade in presence of O₂, CO₂, NO_x, SO₂, and heat resulting in solvent loss, equipment corrosion and generation of volatile degradation compounds. Two types of degradation have been identified in the literature, namely oxidative and thermal degradation. A review of the amine-based solvents, its main degradation products, the apparatus and analytical methods most widely used, as well as the mechanism proposed and kinetic studies are presented and discussed here. Moreover, amines emissions from CO₂ capture units can react in the atmosphere via photo-oxidation and also via NO_X reactions to give nitrosamines and nitramines, which are potentially harmful to the human health and the environment. A discussion of the recent works on atmospheric degradation of amine solvents is also included in this review.