Corrosion Behavior of 304 Stainless Steel in Mixed Amine Absorbents

Against the backdrop of global warming, carbon dioxide capture technologies are advancing rapidly. The chemical absorption method using organic amines as absorbents is one of the most widely used technologies in industry. Mixed organic amine absorbents show great promise for practical application; however, few studies have investigated their corrosion behavior on 304 stainless steel. This paper studied the corrosion behavior of 304 stainless steel in mixed amine solutions through immersion coupon tests, electrochemical tests, and long-term corrosion tests. The results showed that in the mixed amine solution under CO2 saturated load, the corrosion rate of 304 stainless steel increased from 0.0016 mm/a to 0.0065 mm/a (at 30 wt% amine concentration) as the temperature rose from 40 to 60 °C. With increasing amine concentration in the range of 15 to 30 wt%, the corrosion rate first increased and then decreased, reaching a maximum value of 0.0065 mm/a. As the chloride ion concentration increased from 0 to 200 mg/L, the corrosion rate increased from 0.0065 mm/a to 0.0099 mm/a, while the susceptibility to pitting corrosion remained extremely low. Calculated Ea, ΔH‡, and ΔS‡ values jointly demonstrated that the corrosion process under the experimental conditions was predominantly controlled by the interfacial electrochemical charge transfer reaction. After 72 h of immersion, the surface of 304 stainless steel remained in a stable passive state, resulting in very low corrosion rates under all tested conditions and no visible corrosion on the coupon surfaces. Long-term corrosion tests indicated that corrosion predominantly occurred during the initial immersion stage, and the material exhibited good self-passivation performance during long-term service.