Synthesis of novel amino-functionalized ionic liquids and their application in carbon dioxide capture

In this study, four novel amino-functionalized ionic liquids, 1-(2-aminoethyl)-1-methylpiperazin-1-ium amino acid salts ([AEMP][A], wherein [A](-) = [Gly](-), [Ala](-), [Pro](-), [Leu](-)), have been synthesized and characterized, and their physicochemical properties, such as glass transition and thermal decomposition temperatures, were determined. These amino-functionalized ionic liquids, dissolved in solution or supported on SiO2, were applied for carbon dioxide absorption. The results showed that the absorption rate is faster when ionic liquid is supported on silica gel than dissolved in the solution. The absorption capacity reached about 1.5 mol carbon dioxide per mol ionic liquid at ambient pressure, as verified by nuclear magnetic resonance and Fourier transform infrared spectroscopy. Moreover, the amino-functionalized ionic liquid can be recycled under vacuum.