Determination of the oxidative degradation of ethanolamines

Although pure ethanolamines are hazardous substances widely used in chemical processes (e.g., gas sweetening and pretreatment agents), a dedicated assessment of their fire and degradation properties is missing. Within this scope, an experimental analysis was carried out by using a cone calorimeter to quantify the burning characteristics of the ethanolamines most widely used: monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), and methyl diethanolamine (MDEA). The effects of an external heat flux on ignition temperature, maximum mass burning rate, mass loss rate, heat release rate, and exhaust gas composition of liquid samples were observed. The collected data were employed for the development and quantification of an apparent kinetic rate. The resulting rates were validated against empirical data from the literature, showing excellent agreement. Besides, the radical reactions most relevant for the activation of the investigated amines were identified. The experimental overall reaction rates were compared with theoretically based kinetics of the identified reactions to identify the rate-determining step in the process. The results indicate that the hydrogen abstraction from the nitrogen site by HO2 can be considered as the rate-determining step for the MEA and DEA cases, and the same agent is ruling the activation of TEA from a carbon site, highlighting the role of low-temperature chemistry in the ignitability of the ammines. These observations are useful for the accurate modelling and design of chemical processes involving ethanolamines, for the analysis of prevention and mitigation, and for the evaluation of pool fire likelihood and consequence assessment.