Influence of time and composition on A106 steel Corrosion in blended 2-amino-2-methyl-1-propanol and diethylenetriamine solution

During CO ₂ capture, the corrosion of equipment materials is the key factors affecting the economic benefits and safety of CO ₂ capture. This study examined the corrosion behaviours and mechanisms of A106 steel in both a single diethylenetriamine (DETA) system and blended 2-amino-2-methyl-1-propanol (AMP)-DETA amine systems under simulated post-combustion CO ₂ /O ₂ flue gas conditions. The time-dependent corrosion behaviour of AMP-DETA blends was systematically evaluated, enabling comparison with observations from single-amine solutions. The results showed that the corrosion rate of A106 steel was always higher than 3.6 mm/y in 3.0 mol/L DETA solution. With the addition of AMP, the corrosion rate decreased obviously. Compared with 3.0 mol/L DETA solution, the corrosion rate in 2.5 mol/L AMP + 0.5 mol/L DETA solution was about 0.42 mm/y at 360 h, corresponding to an approximate 88% reduction. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses identified Fe ₂ O ₃ and Fe ₃ O ₄ as the main corrosion products, along with adsorbed short-chain amines. This study suggests that AMP-DETA blends may produce a synergistic inhibitory effect on A106 steel corrosion, with AMP addition promoting the formation of protective mixed organic-inorganic surface films. These observations provide mechanistic insights for solvent formulation and material selection in CO ₂ capture processes.