Effects of Cl-ion and temperature variations on steel corrosion in supercritical CO2 saturated aqueous environments
Meifeng Li, Alexander Gross, Ben Taylor, Hao Zhang, Jing Liu
Abstract
This study explored the influence of Cl-ion and temperature variations on the corrosion behavior of pipeline steel in supercritical CO2 (s-CO2) saturated aqueous environments. The steel exposed to the s-CO2 saturated salt solution at 50°C shows a higher corrosion rate (CR) of 5.02 mm/year compared to that exposed to deionized (DI) water, which has a corrosion rate of 1.47 mm/year. This trend is more pronounced at higher temperatures. This performance enhancement is attributed to the formation of a dense and protective FeCO3 film, facilitated by the Cl-ion presence, with a more pronounced effect observed at higher temperatures. The corrosion mechanism, commencing with the impact of Cl- ions on interactions between CO2 and the dissolved HCO3- ions with iron at the steel surface, is comprehensively elucidated via density functional theory (DFT) in s-CO2 systems at varied temperatures. The findings from this study offer valuable insights into mitigating corrosion-related challenges in s-CO2 system.