Investigation of CO2 capture performance of polyamine/organic alcohol ether non-aqueous absorbent regulated by ethylene glycol

Abstract

The use of non-aqueous absorbents has great potential in reducing energy consumption during CO2 capture. However, current obstacles include the formation of precipitation or gelatinous substances after CO2 absorption, which significantly hinder their further application. Moreover, it is crucial to address concerns about insufficient CO2 capture performance and excessive regeneration energy. Therefore, non-aqueous homogeneous absorbents that do not produce precipitates, gels, or solids have gained considerable attention in recent years. In this study, a novel non-aqueous homogeneous absorbent based on polyamine/complex solvent was successfully developed by introducing ethylene glycol into the precipitation-producing polyamine/organic alcohol ether system. This modification resulted in improved CO2 capture performance and reduced regeneration energy. The AEEA/EG/2EE non-aqueous homogeneous absorbent showed a CO2 absorption capacity of 2.67 mol/kg and achieved an impressive regeneration efficiency of up to 81.65 % at the optimal desorption temperature (393 K) in only 40 min, surpassing the conventional MEA/H2O absorbent by a substantial margin (31.65 %). Thermodynamic analysis revealed that this absorbent exhibited a substantial reduction in both sensible and latent heat during CO2 desorption, resulting in a remarkable decrease of 42.8 % in total regeneration energy compared to the conventional MEA/H2O absorbent. The composite solvent EG/2EE was found not to be involved in the reaction process according to the 13C NMR analysis. The main absorption process involved the reaction between organic amine AEEA and CO2 to form carbamate, while the desorption process entailed reverse decomposition of carbamate for CO2 release. Therefore, utilizing ethylene glycol's advantageous properties for regulating polyamine/organic solvent systems presents a promising.