Amine autoxidation in flue gas CO2 capture—Mechanistic lessons learned from other gas treating processes

The use of amines for CO2 capture from flue gases involves one distinct difference and challenge from traditional amine acid gas capture: the presence of dioxygen and its role in the oxidative degradation of the amine. Insights on mechanisms of degradation in flue gas CO2 capture can be obtained from observations of other gas treating processes – primarily trace O2 contamination in “traditional” gas treating amine units as well as the autoxidation of amino acids during oxidative dehydrosulfurization using iron chelates. Three distinct pathways for degradation initiation have been identified: thermal, autoxidation (reaction involving dioxygen) and direct reactions with CO2. This paper will focus on the dioxygen pathway and insights that have been gained from observations of other gas treating processes – primarily trace O2 contamination in “traditional” gas treating amine units as well as the autoxidation of amino acids during oxidative dehydrosulfurization using iron chelates.