Amine-based absorption/stripping is one of the promising technology for CO

2

capture from natural and industrial gas streams. During the process

amines and CO

2

undergo irreversible reactions to produce undesired compounds

which cause corrosion

foaming

increased viscosity and breakdown of equipment

ultimately contributing to the economic loss and environmental pollution. In this study

the thermal degradation of aqueous diethanolamine in the presence and absence of dissolved CO

2

was investigated. The experiments were performed in stainless steel cylinders. The results show that thermal degradation in the absence of CO

2

was a slow process; triethanolamine

and tris(2-aminoethyl)amine were only the degradation products identified in the mixture In addition

the rate of degradation was very low

only 3% degradation was observed after 4 weeks. But in the presence of CO

2

sixteen degradation products were identified

nine of which were new degradation products reported for the first time in this study. The 3-(2-hydroxyethyl)-2-oxazolidinone

1

4-bis(2-hydroxyethyl) piperazine and triethanolamine were the most ab

undant degradation products. The remaining DEA concentration after 4 weeks was about 20% of the total amine concentration. The most probable degradation reactions and their mechanisms are also proposed.