Corrosion in CO2 capture systems. Part I: Initial characterization and the effect of CO2 loading and test temperature

This study provides a comprehensive evaluation of the electrochemical corrosion behavior of low-carbon steel, AISI 316, and AISI 304 stainless steels in CO 2 capture environments using methyldiethanolamine (MDEA) solutions. The effects of CO 2 loading and temperature on corrosion rates were systematically investigated, supported by microstructural analyses (optical microscopy, EBSD, and SEM) and chemical characterization through FTIR, pH, titration, and total carbon analysis. Electrochemical techniques—LPR, EIS, potentiodynamic, and cyclic potentiodynamic polarization—were applied to elucidate corrosion mechanisms. Results show CO 2 loading as the dominant factor influencing corrosion, followed by temperature. For low-carbon steel at 30 °C, CO 2 loading increased the corrosion rate from 0.057 to 18.320 mpy (321-fold), rising further to 46.130 mpy (809-fold) under combined high loading and elevated temperature. AISI 316 exhibited a modest increase at 30 °C (0.045 to 0.057 mpy), a decrease at 80 °C (0.032 mpy), and a 4.6-fold rise (0.205 mpy) under combined stress. AISI 304 showed minimal change at 30 °C (0.0434 to 0.0464 mpy), a slight reduction at 80 °C (0.049 mpy), and a 2.4-fold increase (0.102 mpy) under combined conditions. Previous studies have primarily focused on MEA and DEA systems, whereas the present work offers one of the first comprehensive comparisons of various steels in MDEA-based environments, incorporating detailed characterization of both the amine chemistry and steel microstructure. Through the integration of multiple electrochemical techniques within a unified experimental framework, this study addresses a critical knowledge gap and enhances the understanding of corrosion behavior in CO 2 –amine–metal systems.