Liquid-liquid extraction of neutral degradation products in monoethanolamine absorbtion solution used in carbon dioxide capture

Abstract

The liquid-liquid extraction technique was used to separate the neutral amine degradation products (imidazole, N-acethylethanolamine, 2-oxazolidone and N-(2-hydroxyethyl)-succinimide) from the monoethanolamine (MEA) absorption solution for carbon dioxide capture. The extraction efficiency of neutral MEA degradation products was determined and investigated under various experimental conditions including the effects of 2-ethyl- 1-hexanol diluent alone and extract ant (quaternary amine) in 2-ethy-l-hexanol solution, the absence and presence of MEA in the neutral amine degradation products solutions at different temperature (25℃, 40 ℃ and 60 ℃) and the CO2 loading of 0.05, 0.10 and 0.30 mol/mol amine. All the neutral MEA degradation products were analyzed by using a gas chromatography with flame ionization (GC-FID). The percentages of extraction efficiency of neutral MEA degradation products with extract ant in diluent for N-(2-hydroxyethyl)- succinimide was the most extracted, followed by 2-oxazolidone, imidazole and N-acethylethanolamine, respectively. In case of present MEA solution in aqueous phase, the extraction efficiency of neutral MEA degradation products decreased from 39.77±l.12 %, 27.83±l.66 %, 84.09±0.47 % and 99.44±0.02 % to 16.42±l.36 %, 20.18±l.19 %, 56.93±l.09 % and 72.31±2.54 % for imidazole, N-acethyl ethanolamine, 2-oxazolidone and N-(2-hydroxyethyl)-succinimide, respectively. The extraction efficiency of all neutral MEA degradation with absence and presence MEA increased with increasing extraction temperature. Lastly, the extraction efficiency was decreased dramatically with loading CO2 in neutral MEA degradation products.