Purification of aqueous amine solvents used in post combustion CO₂ capture: A review

The degradation of aqueous amine solvents used in CO₂ capture causes increasing costs and deterioration in long term performance. A very broad range of degradation products, formed by exposure of the amine solution to heat, oxygen and strong acids, have been reported over the past 50 years. To date, industry has generally relied upon purging, filtration, neutralization and thermal reclaiming to reduce the impact of these impurities. However, the high levels of oxygen, SO_x and NO_x in post combustion acid gas capture will mean that other technologies are likely to be more successful. These methods include ion exchange and electrodialysis. This paper will review the major degradation routes leading to corrosive and undesirable by-products as well as the main techniques reported in the literature to reduce the impact of the degradation products on the amine strength.