Study on Degradation Performance of Mixed Amine Absorbent for Carbon Capture From Coal-Fired Flue Gas

ObjectivesThe stability of chemical absorbents is key to the stable operation of chemical absorption carbon capture systems. Therefore, the oxidative and thermal degradation of a novel mixed amine absorbent BA-1 is investigated, along with the evaluation of anti-degradation agents.MethodsThe thermal degradation behavior of BA-1 is investigated using a thermal degradation experimental device under different temperatures (100, 120, and 140 ℃) and CO2 loading concentrations (0-1.5 mol/L). Meanwhile, the oxidative degradation performance of BA-1 is assessed at 65 ℃ under a pure oxygen atmosphere using an oxidative degradation experimental device. The degradation rate and degradation products of BA-1 are analyzed using cation and anion chromatography techniques. The antioxidant effects of 2,5-dimercapto-1,3,4-thiadiazole (DMTD), chelating agent E-1, sodium sulfite (Na2SO3), and acetaldehyde oxime (AAO) are tested.ResultsThe degradation of BA-1 is mainly caused by oxidative degradation. After the addition of E-1, Na2SO3, and AAO, the degradation rate of BA-1 is effectively suppressed. When 0.3% of E-1 is added, the degradation rate of BA-1 over 24 days is only 22.5%, with the degradation inhibition rate reaching 53.8%. The primary degradation products include formate, acetate, oxalate, and nitrate ions. The yield of oxidative degradation products is more than ten times that of thermal degradation products, further confirming that oxidative degradation is the main degradation mechanism of the BA-1 absorbent.ConclusionsThe degradation of mixed amine absorbents is mainly caused by oxidative degradation, and the addition of chelating agents can effectively mitigate absorbent degradation during industrial applications.