Corrosion performance of A3 carbon steel in 30wt.% MEA and AMP-MEA blends for post-combustion carbon capture: Effect and mechanism of corrosion inhibitors

The corrosion behavior of A3 carbon steel in 30 wt.% MEA and AMP-MEA (2:1) blended amine solutions, two typical CO₂ capture solvents for chemical absorption processes, was investigated. The inhibition effects of imidazoline, sodium metavanadate (NaVO₃), and phosphoric acid, triethanolamine salt (P-TEA) were evaluated using various electrochemical testing techniques and immersion corrosion experiments. Results showed that NaVO₃ exhibited the highest corrosion inhibition effect at a concentration level of 1000 ppm, while imidazoline showed limited effectiveness. Both NaVO₃ and P-TEA significantly increased solution resistance and charge transfer resistance, thereby enhancing corrosion inhibition. Additionally, AMP-MEA blends exhibited improved corrosion performance compared to MEA, with the formation of a denser protective layer on the surface of A3 carbon steel. Furthermore, experimental results revealed that NaVO₃ and P-TEA, instead of forming protective oxide or carbonate layers, formed complexes or chelates with iron ions in the solution. These compounds adsorbed onto the carbon steel surface, effectively preventing further corrosion. These findings provide valuable insights into the corrosion behavior of A3 carbon steel in amine-CO₂H₂O systems and underscore the potential of NaVO₃ and P-TEA as effective corrosion inhibitors. This knowledge is crucial for developing enhanced corrosion control strategies in related industrial applications.