The objective of the present study is to evaluate the corrosion properties of carbon steel in
MDEA / H2O / CO2 / O2 / HSSs mixtures related to the CO2 capture process in fossil fuel-fired power plants. Short-term and long-term corrosion tests were performed in 50 wt.% methyldiethanolamine (MDEA) solutions at 50oC 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),
weight loss measurements, and surface analytical techniques (SEM and EDS). The results of
short-term corrosion tests indicated that the addition of CO2 in the MDEA systems significantly
increased the corrosion rate and changed the corrosion behavior from a passive to active state.
However, the corrosion rates of carbon steel did not change significantly with addition of O2
and HSSs. The corrosion rates of carbon steel decreased with time under MDEA/CO2 systems
whereas it maintained the initial values throughout the tests in MDEA/CO2/O2 and
MDEA/CO2/O2/HSSs environments. The order of the corrosivity was MDEA/CO2/O2/HSS >
MDEA/CO2/O2 > MDEA/CO2. The corrosion morphology of carbon steel in MDEA/CO2
systems with O2
and HSSs showed uniform attack with preferential dissolution of ferrite.
Key words: CO2 capture, CO2 corrosion, MDEA, O2, heat stable salt, carbon steel