Thermal Degradation of Monoethanolamine in CO₂ Capture with Acidic Impurities in Flue Gas

Acidic impurities in the flue gas, such as SO₂ and NO_<i>x</i>, are supposed to promote amine degradation in the amine scrubbing process for CO₂ capture. This work investigates the effect of these acidic gases on thermal degradation of MEA (monoethanolamine) by preloading additives, which are Na₂SO₃, SO₂, H₂SO₄, and HNO₃, respectively. MEA concentration was 4.4 mol/kg. CO₂ loading was 0.4 mol/(mol of MEA). Experiment temperature varied from 120 to 150 °C. Ion chromatography (IC) is the main analytical method. The results show that the MEA thermal degradation rate was not affected by these additives. Ammonium became an important product in the experiment with SO₂ or HNO₃ loading. Sulfate was stable in the experiment. In the experiment with SO₂ loading, most of the sulfur remained dissolved in the solution after degradation but could not be detected by IC. A lower pH value will speed up sulfite degradation