Ionic liquids for post-combustion CO_2 absorption

摘要

The present work is a study to evaluate ionic liquids as a potential solvent for post-combustion CO_2 capture. In order to enhance the absorption performance of a CO_2 capture unit, different ionic liquids have been designed and tested. The main goalwas to get a comparison between a reference liquid and selected ionic liquids. As the reference, a solution of 30 w% monoethanolamine (MEA) and water was used. A large range of different pure and diluted ionic liquids was tested with a special screeningprocess to gain general information about the CO_2 absorption performance. Based on these results, a 60 w% ionic liquid solution in water was selected and the vapour-liquid equilibrium was measured experimentally between 40 deg C and 110 deg C. From these curves the enthalpy of absorption for capturing CO_2 into the ionic liquid was determined. With these important parameters one is able to calculate the total energy demand for stripping of CO_2 from the loaded solvent for comparison of the ionic liquidbased solvent with the reference MEA solvent. The energy demand of this 60 w% ionic liquid is slightly lower than that of the reference solution, resulting in possible energy savings between 12 and 16%.