Foaming of CO2-Loaded Amine Solvents Degraded Thermally under Stripper Conditions

Foaming of amine solutions remains a problem for natural gas sweetening and post-combustion carbon capture. New amine-based solutions are being developed to replace monoethanolamine (MBA). This work tested the foaminess of MEA and three alternatives (methyldiethanolamine (MDEA), 1-(2-aminoethyl)piperazine (AEPZ), and 2-amino-2-methyl-1-propanol (AMP)) before and after thermal degradation; two methods were used to describe the foaminess. Foam was only formed after thermal degradation. The first method suggests foaminess, where AEPZ > MDEA > MEA; AMP, by contrast, did not conform to this model and formed a stable foam. The second method, using liquid physical properties, found that solutions that contained more degradation products (MEA, MDEA, AMP) showed different foaminess than those that did not (i.e., changing the chemistry during degradation strongly impacts the foaminess, which is observed). The foaming of these degraded samples demonstrates complexity that cannot be replicated by simple model solutions. Therefore, this study is more representative of the foaming behavior that is observed in industrial cases.