Effect of H2S on Fe corrosion in CO2-saturated brine

• Published in: Journal of materials science 2009-11, Vol.44 (22), p.6167-6181
• Main Authors: Abelev, E., Sellberg, J., Ramanarayanan, T. A., Bernasek, S. L.
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Corrosion; Corrosion effects; Corrosion inhibitors; Corrosion prevention; Corrosion rate; Crystallography and Scattering Methods; Hydrogen sulfide; Inhibition; Ions; Iron; Materials Science; Photoelectrons; Polymer Sciences; Protective; Protective coatings; Pyrite; Saline water; Salt water; Solid Mechanics; X-ray diffraction
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-009-3854-4

The effect of H 2 S at ppm level concentrations on iron corrosion in 3 wt% NaCl solutions saturated with CO 2 in the temperature range of 25–85 °C is examined using electrochemical and surface science techniques. Small H 2 S concentrations (5 ppm) have an inhibiting effect on corrosion in the presence of CO 2 at temperatures from 25 to 55 °C. At 85 °C, however, 50 ppm H 2 S is needed to provide significant corrosion inhibition. At higher H 2 S concentrations, the corrosion rate increases rapidly, while still remaining below the rate for the H 2 S-free solution. Characterization of the iron surfaces after corrosion was carried out using X-ray photoelectron spectroscopy and X-ray diffraction. A sulfur peak (S2p) is observed at a binding energy of 161.8 eV in all cases, attributable to disulfide formation. Corrosion protection in the temperature range 25–55 °C can be attributed to Fe(II) bonded to S and O. At 85 °C, protection of the iron surface is most likely due to FeS 2 formation. Morphological changes on the iron surface after exposure to H 2 S containing solutions were observed by SEM. A thin protective film was seen after exposure to solutions containing 5 ppm H 2 S at 25 °C, while at 85 °C, with the addition of 50 ppm H 2 S to CO 2 -saturated brine solution, a dense protective film was formed on the iron surface.