Evaluation of Alkanolamines Corrosivity During CO₂ Capture and in the Presence of Deep Eutectic Solvent and Ionic Liquid as Inhibitor

Carbon capture and storage (CCS) technologies are vital for reducing carbon dioxide (CO₂) emissions, but corrosion threatens the efficiency and durability of CCS infrastructure. Accurate assessment of alkanolamine solution corrosivity and effective corrosion inhibitors are essential for reliable CCS design. This study evaluates the corrosion inhibition performance of reline (a deep eutectic solvent, DES) and 1-ethyl-3-methylimidazolium trifluoroacetate (an ionic liquid, IL) on carbon steel in carbonated amine solutions using the weight loss method. Before the use of corrosion inhibitors, it presents an experimental investigation of the corrosivity of three alkanolamines commonly used for carbon capture, namely, monoethanolamine (MEA), diethanolamine, and methyl diethanolamine, using electrochemical methods in addition to surface morphology analysis using field emission scanning electron microscopy. Through meticulous experimentation involving the immersion of carbon steel API 5L X52 metal specimens in CO₂-saturated MEA solutions with varying DES and IL concentrations and immersion times, the study uncovers promising insights. The amine concentration used was 10–30 wt% at a temperature of 60–70°C with inhibitor concentration of reline at 0, 30, 50, and 70 wt% and IL at 0.1, 0.3, and 0.5 wt%. A notable reduction in corrosion rates is observed with increasing DES concentrations (a maximum of 77.1% in inhibiting efficiency at 70 wt% DES), underscoring the protective role of DES in inhibiting corrosion. Additionally, the IL was found to be effective as a corrosion inhibitor, with the optimum concentration being at 0.5 wt% giving a maximum inhibition efficiency of 69.8%. This study emphasizes the importance of DES and IL for effective corrosion inhibition in the amine system, thereby ensuring the long-term sustainability and efficacy of CCS infrastructure. 2025 Society of Chemical Industry and John Wiley & Sons, Ltd.