Predicting the effect of reactive impurities on the corrosion rates of carbon steel in CCTUS (C2026-00070)

Ali Eslamimanesh, Mohiedin Bagheri Hariri, Ronald D. Springer, Margaret Lencka, Andre Anderko

It is well established that under CO2 transport conditions, acidic dropout can occur as a separate aqueous phase precipitating out of liquid or supercritical CO2 due to reactions between impurities such as SOx, NOx, H2S, H2O, and O2. Such phases primarily consist of sulfuric and nitric acids. In addition to these impurities, the role of some other components is not yet well elucidated. In particular, certain impurities that are widely used during CO2 capture, such as methanol, amines, and glycols, may play a dual role by facilitating the dropout of corrosive phases or acting as inhibitors. They may inhibit corrosion through scavenging CO2, NOx, and SOx, potentially suppressing the formation of corrosive aqueous phases or changing the phase behavior. The Mixed-Solvent Electrolyte (MSE) model can estimate the speciation chemistry of different types of components across various phases by predicting phases and chemical equilibria including possible redox reactions. This study aims to first understand the chemical behavior of such reactive impurities and then introduces an electrochemical framework that builds upon the MSE thermodynamic framework by integrating speciation predictions with transport phenomena and corrosion layer buildup and dissolution to estimate corrosion rates of carbon steel assets in the presence of corrosion layers.