Prospects of Using Room-Temperature Ionic Liquids as Corrosion Inhibitors in Aqueous Ethanolamine-Based CO2 Capture Solvents

Corrosion is one of the major concerns being encountered in aqueous alkanolamine-based CO2 capture processes. The present work examines the capability of thermally stable and virtually nonvolatile room-temperature ionic liquids (RTILs) to curb corrosion in aqueous monoethanolamine solvents. Four imidazolium-based RTILs with ethyl side chains were chosen for this purpose: [emim][Otf], [emim][DCA], [emim][acetate], and [emim][tosylate]. Carbon steel 1020 has been used as a test material, since it is widely used as construction material in industrial installations. Electrochemical corrosion experiments were carried out using the linear polarization resistance (LPR) technique for measuring corrosion current thus enabling subsequent calculation of corrosion rate via the Tafel fit method. The outcomes illustrate that, out of the tested ionic liquids, [emim][acetate] is the most capable of rectifying the severe operational problem of corrosion in alkanolamine-based state-of-the-art CO2 capture systems.