A review on corrosion inhibitors for high-pressure supercritical CO₂ environment: Challenges and opportunities

The carbon capture and storage (CCS) process significantly contributes in reducing the atmospheric emissions of carbon dioxide (CO₂). During the implementation of the CCS technique, the pipeline corrosion occurring due to the supercritical (SC) CO₂ is a major concern. The corrosion of the steel pipelines is caused by contamination of water that reacts with the CO₂ gas leading to the formation of corrosive species carbonic acid (H₂CO₃). To address to this issue, the strategies used are (i) use of corrosion resistant alloys (CRAs), (ii) corrosion inhibitors, and (iii) the protective layers of iron carbonate (FeCO₃). One of the most important methods is the application of chemical additives to the corrosive medium that dissolve in the environment and adsorb on the target metallic substrate, thereby impacting corrosion mitigation. This article aims to overview the various organic corrosion inhibitors commonly applied in the SC CO₂ corrosion. The requirement of greener inhibitor alternatives is emphasized, and some of the potential research aspects are conceived of. The mechanism of SC CO₂ corrosion, factors affecting and chemistries of inhibitors, and their shortcomings are discussed. This review also discusses the application of computational methods in predicting the inhibitive performance. This is a critical, timely, urgent, and insightful review, identifying successes and shortcomings on the inhibitors available for SC CO₂ medium, and pointing to potential avenues for further investigation.