Heat of Absorption of CO₂ in Phase Change Solvents: 2-(Diethylamino)ethanol and 3-(Methylamino)propylamine

Abstract

Heat of absorption of CO 2 in phase change solvents containing 2-(diethylamino)ethanol (DEEA) and 3-(methylamino)propylamine (MAPA) were measured as a function of CO 2 loading at different temperatures using a commercially available reaction calorimeter. The tested systems were aqueous single amines (5 M DEEA, 2 M MAPA, and 1 M MAPA) and aqueous amine mixtures (5 M DEEA + 2 M MAPA and 5 M DEEA + 1 M MAPA) which give two liquid phases on reacting with CO 2 . All parallel experiments have shown good repeatability. The measurements were taken isothermally at three different temperatures, (40, 80, and 120) °C. The measured differential heat of absorption values were converted into integral values by integration. Heats of absorption of CO 2 in aqueous single amines were affected by changing the solvent composition (large difference in concentrations) and CO 2 feed pressure simultaneously. In addition to these two parameters, it also depends on temperature and the type of amine used. Tertiary alkanolamine (DEEA) has shown greater dependency on these parameters compared to the diamine (MAPA) containing both primary and secondary amine functional groups. In aqueous amine mixtures, heats of absorption depend on CO 2 loading, temperature, and composition of the constituent amines in the mixture. All measured heat of absorption data were compared with 30 mass % MEA used as a base case.