Corrosion behaviour of X65 carbon steel in supercritical-CO2 containing H2O and O2 in carbon capture and storage (CCS) technology

Corrosion behaviour of X65 carbon steel in supercritical-CO2 (SC-CO2) containing H2O and O2 was studied by weight loss test, electrochemical measurements, and surface analysis. A setup was developed for in situ electrochemical measurements in H2O-saturated SC-CO2 phase by using Ag/AgCl reference electrode. It is demonstrated that there is no essential difference in the electrochemical corrosion mechanism between SC-CO2 and non-SC-CO2 environments. The presence of small amount of O2 inhibits the formation of protective FeCO3 film and promotes the formation of non-protective Fe oxide, which leads to obvious increase of corrosion rate in SC-CO2 phase.