Evaluation of 3-dibutylamino-propylamine aqueous solution for CO2 capture: Promoting the energy-saving regeneration through self-extraction regulation

[Display omitted] •A novel DBAPA absorbent featured ‘self-extraction’ property was used for CO2 capture.•The saturated solution could regenerate efficiently by thermal desorption at 98 °C.•The self-extraction mechanism was clarified by theoretical and experimentalanalysis.•The polarity reversibility of DBAPA resulted in the performance of self extraction. Due to the strong bonding of amino groups with CO2, the alcohol amine-based absorbents for CO2 capture suffer the disadvantage of high regeneration temperature and energy consumption. To promote the energy-saving regeneration, a novel 3-Dibutylamino-propylamine (DBAPA) aqueous absorbent featured ‘self-extraction’ property was proposed, for which the fresh solution maintained liquid–liquid two-phase and became homogeneous after CO2 absorption. Due to the self-extraction regulation, its CO2 products could be regenerated at a low temperature below the boiling point of water (98 °C). It kept 81.98 % of its initial loading (1.27 mol·mol−1) after the first regeneration and maintained 73.17 % after the sixth regeneration cycle at 98 °C, much higher than that of MEA (28.96 %). Based on the results of 13C NMR and quantum chemical calculations, the self-extraction regulation mechanism of DBAPA for CO2 capture was clarified. It was proved that there was a vast polarity difference between DBAPA and H2O, resulting in phase separation before absorption. With the increasing CO2 loading, CO2 reacted with DBAPA to form DBAPA-carbamate, and the solution became homogeneous because of the increasing polarity of the CO2 products and the strong hydrogen bonds between the products and H2O. The amine recovered to its low polarity during the desorption process, and the intermolecular hydrogen bonding with H2O decreased. DBAPA separated from the main solution to the upper phase, promoting the regeneration rate at 98 °C. Based on this self-extraction property, the regeneration energy consumption of DBAPA was estimated to be 1.89 GJ·ton−1 CO2, which was much lower than that of MEA (3.77 GJ·ton−1 CO2). The results indicated that the novel DBAPA aqueous absorbent with self-extraction characteristics had good energy-saving potential for CO2 capture.