Degradation and Corrosivity of MEA with Oxidation Inhibitors in a Carbon Dioxide Capture Process

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The effect of oxidation inhibitors, EDTA, formaldehyde and Na₂SO₃, on the oxidative and thermal degradation and the corrosivity of MEA were investigated and the products of oxidative and thermal degradation of MEA were analyzed. There was no difference in the CO₂ absorption/desorption rates among MEA solutions with or without the oxidation inhibitors. The oxidation inhibitors prevented the oxidative degradation of MEA and the extent of prevention was in the order EDTA » formaldehyde > Na₂SO₃. Among the products of the oxidative degradation of MEA in the oxidation condition, formate and acetate were the dominant degradation products, and EDTA decreased the products of MEA much more than any other inhibitors. Oxidation inhibitors had no effect on the thermal degradation of MEA and there were no oxidative products, such as carboxylic acids (glycolate, formate, acetate, and oxalate), and nitrogen products (nitrite and nitrate) in thermal degradation conditions. The corrosion rate of MEA with the inhibitors was in the order Na₂SO₃ < EDTA < formaldehyde. Na₂SO₃ and EDTA decreased the corrosion rate of the MEA solution while formaldehyde slightly increased the corrosion rate.