Advancing the mechanistic understanding of corrosion in supercritical CO2 with H2O and O2 impurities

The effects of impurities H2O and O2 in transported s-CO2 on the corrosion modes and kinetics of pipeline steels were investigated using rotating cage methodology and in-situ electrochemical noise (EN) technique in an autoclave. In s-CO2 with H2O and O2, pressure acts as a key factor on the solubility of H2O in s-CO2 and corrosion extents, and there is a threshold pressure (∼10 MPa) above which corrosion rate remarkably increases with pressure. In-situ EN results in different CO2 environments further reveal that corrosion in s-CO2 with H2O and O2 is dominated by gas chemical reactions rather than electrochemical reactions.