DOI: 10.1177/1478422x261504097 ISSN: 1478-422X
Combined impurity effects on carbon steel corrosion in supercritical CO
2
systems
Anusuya Talukdar, Kapil Kumar Gupta, Peter Fojan, Leonid Gurevich, Rudi P. Nielsen, Marco Maschietti, Rajan Ambat
The presence of water and impurities in supercritical CO
2
(sCO
2
) can significantly increase corrosion risk for carbon steel used in carbon capture, utilisation and storage (CCUS) systems. Acidic impurities such as SO
x
, H
2
S and NO
x
may dissolve in condensed water to form corrosive species, while brines can originate from residual formation water or operational carryover. This study investigates the combined effects of H
2
O, HNO
3
, SO
2
, H
2
S and NaCl on the corrosion behaviour of 1Cr carbon steel in sCO
2
–brine environments (100 bar, 35–55 °C) under both full-immersion and limited-wetness conditions. Corrosion was characterised using weight-loss measurements, SEM, AFM, XRD and contact angle analysis. Corrosion behaviour was controlled by impurity interactions, corrosion product stability, chloride content and water availability rather than pH alone. At 35 °C, HNO
3
-containing systems produced the highest corrosion rate (3.4 mm y
−1
), while SO
2
and H
2
S systems showed rates below 0.5 mm y
−1
. At 55 °C, corrosion rates in NaCl-containing multicomponent systems increased from 1.6 to 8.6 mm y
−1
after 7 days. Continuous immersion caused higher corrosion rates, whereas thin films promoted localised attack. The novelty lies in directly comparing bulk immersion and thin-film corrosion under identical multicomponent impurity conditions.