Comparison of corrosion behavior of X52 steel in liquid and supercritical CO2 transport environments with multiple impurities

In this study, the corrosion behavior of X52 steel in liquid and supercritical CO₂ environments with different water contents and coexistence of O₂, SO₂, NO₂ and H₂S gas impurities was investigated by means of mass loss method, surface analysis techniques and water chemistry simulations. The results show that benefiting from more corrosive substances and more corrosive aqueous phase, the corrosion degree of X52 steel in a liquid CO₂ environment is larger than that in a supercritical CO₂ environment. The formation of corrosion products is not affected by the changed CO₂ phase state environment but is greatly affected by the water content in CO₂ fluid. The impurities, the product of impurity reactions and the further oxidation of corrosion products jointly dominate the formation of corrosion products on the steel.