Addition of potassium iodide reduces oxidative degradation of monoethanolamine (MEA)

Abstract

We introduce the addition of stable salts to aqueous MEA as a way of inhibiting oxidative degradation reactions. We performed oxidative degradation studies in aqueous MEA containing sodium chloride (NaCl) and potassium iodide (KI). These “salted amine solvents” have been shortened to SAS. The 2.0 %wt. and 1.0 %wt. KI SAS show remarkable oxidative degradation behavior. Loss of alkalinity after 42 days of oxidative degradation experiments with the 1.0 %wt. KI SAS was of 4%, whereas that of aqueous MEA was of 40% after only 21 days. We evaluated how the addition of stable salts impacts CO2 solubility, viscosity, and thermal degradation and corrosion behavior and verify negligible deviations from aqueous MEA. Thus, addition of stable salts affects oxidative degradation phenomena without deranging CO2 solubility or mass transfer rates. With the promising inhibition behavior of KI on MEA degradation, this work presents the initial steps towards making it a commercially viable degradation inhibitor.