CO2Capture Process and Corrosion of Carbon Steel in [Bmim][Lys]-K2CO3 Aqueous Solutios

The corrosion of carbon steel in carbonated 1-butyl-3-methylimidazolium lysinate ([Bmim][Lys])potassium carbonate (K2CO3) aqueous solution was investigated by using a CHI602E electrochemical analyser. The time-dependent absorption capacity, polarization behaviour and corrosion rate of carbon steel in carbon dioxide (CO2)-loaded K2CO3 aqueous solution and [Bmim][Lys]-K2CO3 aqueous solution were measured. The effects of temperature, the mass fraction of [Bmim][Lys]/K2CO3 and CO2 loading on the corrosion rate were demonstrated. The pH values of CO2-loaded K2CO3-[Bmim][Lys] aqueous solutions were measured, and the variations in H+ concentration and the effect of H+ concentration on the corrosion rate were analysed. Our experiments showed that when activated by [Bmim][Lys], K2CO3 aqueous solution demonstrated a higher CO2 absorption capacity, higher CO2 absorption rate and lower corrosion rate for carbon steel. Compared with the commercially applied diethanolamine (DEA, 3%) - K2CO3 (25%) aqueous solution, the [Bmim][Lys] (7.5%)-activated K2CO3 (25%) aqueous solution can not only achieve a higher CO2 absorption capacity, lower the corrosion of carbon steel and achieve a similar CO2 absorption rate but also decrease the energy cost due to its advantages of higher concentration and lower water content; thus, the investigated solution has very good application potential in the CO2 capture process.