CO2 absorption by biphasic solvents: Mixtures of 1,4-Butanediamine and 2-(Diethylamino)-ethanol

• 2B4D had 46% higher cyclic loading, 48% higher cyclic capacity than 5 M MEA.
• Separation was due to the limited solubility of DEEA and the fast reaction rate of BDA with CO2.
• In lower phase, BDA, carbamate and bicarbamate mole fractions were 16.8%, 55.8% and 27.4% at 0.446 total loading.

The cyclic capacity and cyclic loading of mixtures of 1,4-Butanediamine (BDA) and 2-(Diethylamino)-ethanol (DEEA) with different concentrations were compared using a fast screening facility. The biphasic solvent, 2 M BDA blended with 4 M DEEA, was found to have higher cyclic capacity and loading than other concentrations and 5 M MEA. The individual amine distributions in the upper and lower phases were measured by DX-120 ion chromatography (IC), with a formation mechanism then proposed for the biphasic solvents and verified with solubility experiments. The reaction products in the two phases were measured by a JNM ECA-600 nuclear magnetic resonance spectrometer (NMR).