Novel amino acid ionic liquids as messenger of multi-tertiary-amines solutions for highly efficient capture of CO2

Carbon capture, utilization, and storage (CCUS) are among the key technologies to achieve large-scale carbon emission reduction globally. Amino acid ionic liquids (AAILs) featuring biodegradability and biological activity are capable as eco-friendly absorbents for CO2 capture. Herein, a series of novel AAILs are proposed via one-step hydrolysis of cheap lactams, which can act as messengers to facilitate aqueous solution of multi-tertiary-amines fast and pronounced absorption of CO2. Dynamic absorption experiments were carried out to indicate that [N1111][Maba]-PMDETA-50% showed a larger apparent absorption rate constant (0.282 min−1) than that of MDEA solution (0.043 min−1), demonstrating the activated role of AAILs. [N1111][Maba]-PMDETA-50% shows the exceptional absorption capacity of 0.162 g (1.0 bar) or 0.095 g (0.1 bar) of CO2 per g absorbent at 313.2 K, respectively, surpassing all the reported formulated solution. The facilitated absorption mechanism is also illuminated from the NMR spectra. The regeneration heat (equal to absorption enthalpy) was calculated to be −55.7 kJ·mol−1 from absorption isotherm of three different temperatures. The recyclability was evaluated from the vacuum regeneration (ten consecutive absorption–desorption cycles) and dynamic thermal regeneration, achieving the regeneration efficiency of more than 95 % and 99 %, respectively. All these experimental data indicate that the AAIL-based multi-tertiary-amines aqueous solution may be good candidate absorbent in terms of rapid efficient capture of CO2.