Effect of 1-Methylimidazole on CO2 Absorption by Diethylenetriamine Aqueous Solutions

Phase-splitting absorbents represent a promising technology in relation to the low energy levels required during the CO2 capture process. In this work, 1-methylimidazole was added to a diethylenetriamine (DETA) aqueous solution for high CO2 loading via the phase splitting of absorbents during CO2 absorption. Phase splitting was observed during the absorption process when the loading of CO2 reaches a value suitable for the mixture f DETA, 1-methylimidazole, and water. The distribution of individual components in each phase was measured according to the total organic carbon and GC. DETA and CO2 were concentrated in the bottom phase and 1-methylimidazole was mostly in the top phase. From these results, it was presumed that phase splitting during CO2 absorption was mainly due to the solubility limitation of DETA carbamate into 1-methylimidazole. The volume reduction in the bottom phase by phase-splitting is expected to reduce the heat duty during the regeneration process.