Aqueous solutions of sterically hindered amino acid ionic liquids for rapid and efficient capture of CO2

Sterically hindered amines (SHAs), such as 2-amino-2-methyl-1-propanol (AMP), are an important subclass of conventional absorbents with large CO 2 capacity, while ionic liquids (ILs) are novel materials with unique physiochemical properties including negligible vapor pressure and high thermal stability. To combine the characteristics of these two kinds of CO 2 absorbents together, we proposed and successfully synthesized a series of new sterically hindered amino acid ionic liquids (SHAAILs). These SHAAILs (aqueous solutions) were proved to have excellent physiochemical properties, large CO 2 capacity (up to 0.92 mol mol −1 at 313.2 K, 1.0 bar), and fast absorption rate (greater than AMP). Dynamic absorption and thermal regeneration experiments were done to further illustrate the capability of SHAAILs in absorbing and desorbing CO 2 , and [N 1111 ][β-iPrNH-Ala] was found to be an excellent CO 2 absorbent owing to its suitable steric hinderance and also its ionic nature. NMR analysis confirms that the SHAAILs of suitable steric hinderance undergo the carbamate-mediated rapid hydrolysis mechanism in absorbing CO 2 . Due to the comprehensive advantages of SHAAILs, they are believed to have great potentials as efficient CO 2 absorbents in practical applications.