Vapor Liquid Equilibrium of Aqueous Diethanolamine Solution for Carbon Dioxide Capture Processes

Abstract

Objectives : Acid gases such as carbon dioxide (CO₂) and hydrogen sulfide (H₂S) that cause global warming are mainly generated in chemical processes. As a technology for reducing acid gas, the post-combustion capture process is representative. Aqueous alkanolamine solution, which is mainly used in the carbon dioxide absorption process, is used as the most representative chemical absorbent. Thermodynamic data of vapor-liquid equilibrium are important for the economics of process design and operation. In this study, vapor-liquid equilibrium data of water + DEA are measured so that DEA, a secondary amine, can be used in the carbon dioxide absorption process, so that it can be used for designing a new carbon dioxide absorption process.Methods : Vapor-liquid equilibrium data of a mixture of water + DEA (diethanolamine) were measured under isothermal conditions of 393.15 K using HSGC (Headspace Gas Chromatography).Results and Discussion : The measured vapor-liquid equilibrium data were correlated using NRTL, an activity coefficient model. In addition, as additional thermodynamic data of the absorbent mixture, the density of the DEA aqueous mixture was measured at a temperature of 303.15 K to 333.15 K using a density meter (Anton Paar DMA4500). The measured density data of the mixture was converted into excess volume, and the excess volume data was correlated using the Redilchi-Kister-Muggianu equation. Using the measured water+DEA vapor-liquid equilibrium data, it is expected to reducing the design cost and operating cost of the carbon dioxide absorption processes.