Neutralizing amines effect on corrosion process of carbon steel exposed in acid sour media

摘要

To control the corrosion process in primary distillation towers by the influence of acid sour media (HCl+H_2S), neutralizing compounds are widely used in oilfield. Amines typically used are Monoethanol Amine (MEA), Ethylenediamine (E), Ethylenediamine at 60% (E60) and 2-ethylhexillamine (2-EH), being the first one the most used. In this work Electrochemical Impedance Spectroscopy (EIS) technique is used to study the amines concentration effect on carbon steel corrosion process in sour solution (0.5 M HCl + 500 ppm of H_2S at 40 ℃, pH 2). The quantitative analysis of EIS diagrams showed an active behavior of the interface without amine. Furthermore, metal activity increases in presence of MEA and E. However, at different dosages (5, 15 and 30 ppm) both E60 and 2-EH amines, exhibit a positive effect to control corrosion. Finally, EIS analysis is supported by scanning electron microscopy (SEM) characterization.