Experimental and theoretical investigation of a novel multi-amino-functionalized ionic phase change absorbent for highly efficient CO2 capture

A great potential for CO2 capture is that combining the advantages of both the structural tunability of functionalized ionic liquids and low energy consumption of phase change absorbent. In this study, a novel multiamino groups functionalized ionic liquids [TEPAH][Lys] was synthesized and dissolved in NPA and H2O to achieve high absorption loading with low energy consumption. The experimental results demonstrated that the [TEPAH][Lys]/NPA/H2O exhibited a remarkable CO2 absorption loading of 2.93 mol CO2 center dot mol absorbent-1 with 97.54 % of the CO2 products were concentrated in the lower phase, while the volume fraction was only 38 %. Meanwhile, the lower phase displayed low viscosity and excellent fluidity. The first desorption efficiency was as high as 81.19% when the volume ratio of the added upper phase to the lower phase is 26.32 %, and the recycling efficiency could maintain above 81.15 % after fifth absorption-desorption cycles.13C NMR analysis revealed that the [TEPAH][Lys]/NPA/H2O absorbent was able to react with CO2, the CO2 products of carbamate, protonated amine, and propyl carbonates were presented only in the lower phase while the upper phase was almost exclusively NPA. The quantum chemical calculations revealed that CO2 products have greater polarity and density, resulting in higher solubility in water than NPA. The energy consumption was estimated as 2.60 GJ center dot ton-1 CO2, which was approximately 33.50 % lower than that of 30 % MEA (3.91 GJ center dot ton-1 CO2) under similar conditions. Overall, [TEPAH][Lys]/NPA/H2O phase change absorbent exhibits high CO2 absorption loading and low energy consumption, making it extremely potential for industrial carbon capture applications.