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

• Corrosion differences of X52 steel in impure supercritical and liquid CO 2 environments are compared. • The corrosion of X52 steel is more serious in liquid CO 2 environment with multiple impurities. • The formation mechanism of corrosion products in low and high water content environment is determined. • The reasons for corrosion difference in supercritical and liquid CO 2 environments are revealed. In this study, the corrosion behavior of X52 steel in liquid and supercritical CO 2 environments with different water contents and coexistence of O 2 , SO 2 , NO 2 and H 2 S 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 CO 2 environment is larger than that in a supercritical CO 2 environment. The formation of corrosion products is not affected by the changed CO 2 phase state environment but is greatly affected by the water content in CO 2 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.