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

Abstract

Heat of absorption of CO2 in phase change solvents containing 2-(diethylamino)ethanol (DEEA) and 3- (methylamino)propylamine (MAPA) were measured as a function of CO2 loading at different temperatures using a commercially available reaction calorimeter. The tested systems were aqueous single amines (5M DEEA, 2M MAPA and 1M MAPA) and aqueous amine mixtures (5M DEEA + 2M MAPA and 5M DEEA + 1M MAPA) which give two liquid phases on reacting with CO2. All parallel experiments have shown good repeatability. The measurements were taken isothermally at three temperatures in the industrially important temperature range of 40-120oC. The measured differential heat of absorption values were converted into integral values by integration. Heats of absorption of CO2 in aqueous single amines were affected by changing the solvent composition (large difference in concentrations) and CO2 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 CO2 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.