Handling heat-stable salts in post-combustion CO2 capture: A detailed survey

Abstract

The generation of heat-stable salts (HSSs) in alkanolamine solutions for CO₂ capture processes, which is adapted for power plant technologies, exists irrespective of the class of amine solution used for the capture process. Their presence do not only trigger decrements in the CO₂ absorption capacities of the solvents and contribute to further alkanolamine degradation, but also result in foaming and loss of solvents, which impacts system economics and threatens the environment. HSSs also promote the corrosiveness of the metallic structures of capture systems by lowering the pH and increasing the conductivity of the absorbent solutions. Overall, these effects substantially subvert the reliability and integrity of CO₂ capture units. This survey affords sufficient background on the existence of HSSs by unraveling the flow process in a typical alkanolamine-based CO₂ capture unit with respect to their formation points and potential threats. Furthermore, the major HSSs removal and alkanolamine reclamation methodologies (electrodialysis, distillation, ion exchange, electromagnetic separation, and solvent extraction) were comprehensively explored. We believe that this review paper will benefit researchers across disciplines as we continue to explore new and complex solvent formulations to minimize the cost of CO₂ capture while maximizing efficiency. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.