CO 2 absorption using biphasic solvent: Blends of diethylenetriamine, sulfolane, and water

We report a new cyclic process using a biphasic solvent as a potential technology for energy conservation during CO2 capture. In this work, a biphasic solvent comprising diethylenetriamine (DETA), sulfolane, and H2O was used. The solubility of CO2 in the blends of DETA-sulfolane-H2O was measured at different temperatures (313.2–393.2 K) and CO2 partial pressures (up to 400 kPa). Distributions of components at different CO2 loadings were analyzed for both phases by total organic carbon and elemental analyses. The results indicate that DETA and CO2 were concentrated in the upper phase and sulfolane stayed mostly in the lower phase. The separation of the biphasic system was due to the limited solubility of the carbamate, dicarbamate, and tricarbamate products that formed when DETA reacted with CO2 in sulfolane. A biphasic cyclic process with a blend of 20% DETA + 40% sulfolane + 40% H2O in absorption, and then, 60% of a blend with 30% DETA + 10% sulfolane + 60% H2O regenerated in desorption was established. The cyclic loading of the new process was 35% higher than that of 30% monoethanolamine (MEA) aqueous solution.