2-Ethanolamine (MEA) degradation has been studied under varying conditions of relevance to postcombustion CO 2 capture. Degradation experiments performed in the laboratory were chosen to be representative of the conditions in a CO 2 capture plant facility. The thermal degradation of MEA was investigated in closed-batch experiments at 135 °C at different loadings. MEA degradation was also studied in oxidative conditions without additives or by adding FeSO 4 /fly ash. These experiments were compared with three MEA campaigns performed in pilot plants at Tiller (Norway), Esbjerg (Denmark), and Longannet (U.K.). The same analytical procedures were used to identify and quantify the main degradation compounds. Mechanisms are also proposed to account for the observed degradation products. For the Tiller campaign 99.7% of nitrogen containing compounds in the liquid at the end of the campaign was accounted for by the solvent and quantified degradation products.

Oxidative degradation experiments on 2-ethanolamine (MEA) were performed at four different oxygen concentrations and at two temperatures. MEA loss and degradation product build-up were measured. Increasing the temperature from 55 to 75 °C was shown to have higher impact on the MEA loss than increasing the oxygen concentration from 21 to 98%. Liquid end sample analyses were performed for all experiments and overall nitrogen balance tests were conducted for the experiments at 21% O2 (run 2), 50% O2 and 98% O2. Analysis of liquid and gas phase ammonia and MEA in the solvent was found to give a good overall picture of degradation in the MEA system. The degradation products formed at the different oxygen concentrations were the same as described in earlier literature. However, it was found that oxygen affects the formation of the individual degradation products differently. At 75 o C the development of degradation product concentrations with time was more complex. Laboratory reaction experiments were used to verify the formation of certain degradation products from some of the suggested mechanisms.

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Oxidative degradation experiments on five amines and two amino acids were performed in a new closed setup at atmospheric pressure. For most of the amines/amino acids significant degradation was not present under these conditions, except for MEA and MMEA. The degradation compounds found seem to follow the same patterns as described in literature. Volatile compounds as ammonia and alkylamine play an important role in understanding the initial degradation mechanisms. For MMEA, methylamine and ammonia were found in the same order of magnitude. Oxygen stochiometry of the degradation compounds could not be explained by initial air in the system. Oxygen in some of the degradation compounds could come from oxygen diffusing into the system as seen from proposed model and/or water reacting with iminium giving aldehyde and amine/ammonia. Temperature and dissolved metal seemed to influence oxygen and degradation rate for the MEA experiments.

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