Effect of impurity on the corrosion behavior of X65 steel in water-saturated supercritical CO2 system

A range of impurities from various CO2 capture processes may exist in supercritical CO2 transport pipeline in carbon capture and storage process. In this regard, the corrosion behavior of X65 steel in water saturated supercritical CO2 containing O-2, H2S, SO2 or NO2 impurity was investigated using weight loss measurement and surface characterization. The corrosion impact factor was defined which showed that NO2 or SO2 had the greatest influence on the corrosion of X65 steel, followed by H2S and O-2. Localized corrosion occurred in water-saturated supercritical CO2 system containing NO2 with or without other impurities. Low concentrations of impurities could notably change the corrosion rate and the characteristics of corrosion scale via changing the corrosion mechanism, and thus the corrosion effect of CO2 weakened in water -saturated supercritical CO2 system containing impurities. (C) 2016 Elsevier B.V. All rights reserved.