Effect of Oxygen and Heat Stable Salts on the Corrosion of Carbon Steel in MDEA-Based CO2 Capture Process

Amine scrubbing CO₂ process used in fossil fuel-fired power plants is significantly different with refinery applications, such as oxygen-rich environment and heat stable salts (HSSs) from products of combustion (NO_x, SO_x, particulates, etc.). The objective of the present study is to evaluate the corrosion properties of carbon steel in CO₂/O₂/MDEA/HSSs mixtures related to the CO₂ capture process in fossil fuel-fired power plants. In this work, short-term and long-term corrosion tests were performed in 50wt.% methyldiethanolamine (MDEA) solutions at 50^oC under atmospheric pressure with different combinations of CO₂, O₂ and HSSs (bicine, formate, sulfate). Corrosion behavior of carbon steel was evaluated by using electrochemical methods (LPR, EIS, and cyclic polarization test) and surface analytical techniques (SEM, EDS, and Raman). The test results indicated that CO₂ is the primary factor to induce corrosion in MDEA solution. The promotion of O₂ and HSSs was not obvious at initial period of corrosion, but with the passage of time, it became a dominant factor determining corrosion mechanism and accelerating corrosion process.