Solubility measurements and reaction mechanism of carbon dioxide into amine solution

Abstract

Recently, many environmental problems have been reported, which are caused by the utilization of fossil fuel. Especially, carbon dioxide from fossil fuel combustion is thought to be a main source of the global warming, to affect the global environment. Therefore, the removal of acid gases from refinerty and natural gases has been of great importance. Aqueous solutions of alkanolamines have been widely used to the acid gas absorption. Particularly, the growing interest in aqueous solutions of sterically hindered amines for the use in gas treatment processes is due to the high capacity, selectivity, and relatively high absorption rates. In this study, macroscopic and microscopic analysis of pure and $CO_2$ absorbed amine solutions were performed to reveal the $CO_2$-amine reaction mechanism. For macroscopic analysis, physical properties of amine solutions, solubility of $CO_2$ in amine solutions, and reaction kinetics were carefully measured. For microscopic analysis, pure and $CO_2$ absorbed amine solutions were analyzed through FT-IR and NMR spectroscopy. Moreover, macroscopic and microscopic results were compared and analyzed to identify the reaction mechanism. First, physical properties of 2-amino-2-ethyl-1,3-propanediol (AEPD) solutions such as density, viscosity, and surface tension were measured at 303.15, 313.15, 323.15, 333.15, and 343.15 K with AEPD concentrations ranging from 20 to 100 mass %. All physical properties were correlated by appropriate equations and correlation parameters were obtained. Measured and calculated values agreed well within 0.07% for density, 0.56% for viscosity, and 0.42% for surface tension in AADs. The solubility of carbon dioxide in aqueous AEPD solutions was measured at 313.15, 323.15, and 333.15 K over the partial pressure of carbon dioxide ranging from 1 to 3000 kPa. The concentrations of aqueous AEPD solutions were 10 and 30 mass %. As a result of comparing the solubilities of carbon dioxide in aqueous 10 mass % AEPD ...