Stability of aqueous amine solutions to thermal and oxidative degradation in the absence and the presence of CO2

The stability to thermal and oxidative degradation of five single amine aqueous solutions (2-amino-2-hydroxymethyl-1,3-propanediol (AHPD), piperazine (Pz), 2-amino-1,3-propanediol (Serinol), 2-amino-2-methyl-1-propanol (AMP) and monoethanolamine (MEA)) and one mixed aqueous solution (AHPD + Pz), in the absence and the presence of CO2, was investigated by high-performance liquid chromatography. The results showed that the presence of O2 and CO2 influenced significantly the degree of thermal degradation. The sterically hindered alkanolamines investigated (AMP and AHPD) were found more resistant to thermal degradation than conventional (unhindered) amines. However, in the absence of CO2, the oxygen degraded them more significantly. The addition of Pz to AHPD solution reduces the AHPD oxidative degradation. It was concluded that AHPD + Pz amine aqueous blend could be a potentially interesting absorbent to replace MEA for industrial CO2 capture applications, especially using membrane contactors.