CO₂ loading-dependent corrosion of carbon steel and formation of corrosion products in anoxic 30 wt.% monoethanolamine-based solutions

Corrosion of A106 carbon steel in anoxic CO₂-loaded 30 wt.% monoethanolamine-based solutions (a corrosive solvent for post-combustion CO₂ capture) with CO₂ loadings ranging from 0.24 to 0.53 mol CO₂/mol amine is investigated. The results show that corrosion and formation of a protective layer of corrosion products on the A106 surface are strongly CO₂ loading-dependent. That is, initial corrosion is accelerated with increased CO₂ loading. However, the formation of chukanovite and subsequently siderite, which dramatically inhibits the corrosion, was promoted with increasing CO₂ loading. Chukanovite is a metastable intermediate corrosion product which transforms into siderite. Possible mechanisms are discussed.