Post-combustion CO₂ capture using aqueous amine solutions has gained significant popularity in recent years, owing to their exceptional absorption capacity, rapid reaction kinetics, and ability to regenerate efficiently. However, a major challenge lies in the corrosive nature of amines after reacting with CO₂, which can lead to significant operational issues in process equipment. Beyond CO₂, the oxidative degradation of amine solvents further influences corrosion. This degradation is accelerated by oxidative agents, such as O2, SOx, and NOx impurities in flue gas, which interact with amine solutions to form various degradation by-products .
This study focused on investigating the corrosion behavior of 316L and 304L stainless steels (SS316L and SS304L)—widely used in carbon-dioxide capture units—when exposed to both degraded and non-degraded MEA aqueous amine solutions containing SOx and NOx pollutants, under both CO2-loaded and unloaded conditions. The research assesses the impact of MEA degradation on the corrosion characteristics of these stainless steels, using Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy. Scanning electron microscopy (SEM) was used to gain further insights into corrosion mechanism.
The results revealed that the degradation of the amine solutions, whether CO₂-loaded or unloaded, promoted the corrosion in both stainless steels. Corrosion rates were higher in degraded solutions compared to non-degraded ones, indicating reduced corrosion resistance. This was also verified by the lower total impedance values observed in Bode diagrams.
Funding: This work has received funding from the European Union's Horizon Europe research and innovation program under grant agreement No. 101075727. The views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or European Climate, Infrastructure and Environment Executive Agency (CINEA). Neither the European Union nor the granting authority can be held responsible for them.
