Corrosion Mechanism of 20# Carbon Steel and 30408 Stainless Steel in Aminoethylethanolamine Solution: Effect of SO ₂ and Oxidative Degradation Products

ABSTRACT The corrosion characteristics and mechanism of CO 2 capture equipment materials in organic amines are the key issues affecting the safety of carbon capture equipment. This work investigated the effect of SO 2 on the corrosion mechanism of 20# carbon steel and 30408 austenitic stainless steel in the aminoethylethanolamine (AEEA)‐CO 2 ‐O 2 system, and studied the corrosion characteristics and mechanism of 20# carbon steel in both (i) freshly prepared AEEA solution and (ii) AEEA solution after 120 h of degradation. Weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy, and various product scale characterization methods such as scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis were applied. The results revealed that the corrosion rates of both 20# and 30408 steel increased significantly with the addition of 0.5% SO 2 in a 30% AEEA‐12% CO 2 ‐6% O 2 environment. The corrosion rate of 20# steel in dirty solution (after oxidative degradation) without SO 2 was slightly lower than that in fresh solution. With the addition of 0.5% SO 2 , the average corrosion rate of 20# steel in fresh solution was 0.174 mm/y, and in dirty solution containing degradation products was 0.012 mm/y; the corrosion rate in dirty solution was significantly reduced compared to fresh solution. These findings indicated that the organic amine degradation products generated under the conditions had a significant corrosion inhibition effect on 20# steel.