LAUSR

Abstract To mitigate CO 2 release, large-scale post-combustion capture with amine solvents is essential. To achieve capital cost savings, carbon steel infrastructure can replace stainless steel if corrosion by CO 2 -loaded amine solvents is controlled. A coating, to protect the carbon steel, formed using an amine (or additive) is beneficial because it can be regenerated. Siderite has been shown to form a protective crystalline product layer, created when Fe oxidised at the surface reacts with carbonate ions. Tertiary or sterically-hindered CO 2 -loaded amine solutions can form this layer. Herein siderite was prepared on carbon steel substrates from 5 M methyldiethanolamine (MDEA), 5 M 2-amino-2-methyl-1-propanol (AMP), and 1 M K 2 CO 3 at 40 and 80 °C. At 40 °C, K 2 CO 3 produced the most successful protective siderite layer; by contrast, the amine solutions developed layers with interlocking crystals at 80 °C. After siderite formation, these substrates were tested in 2.5 M MEA and AEPZ, both highly corrosive but with more desirable capture kinetics. At 80 °C, substrates pre-treated with MDEA or AMP showed good resistance against the corrosive actions of MEA and AEPZ for four weeks. The siderite layer reduced Fe oxidation at the surface and ingress of solution species thereby ceasing contact and corrosion.