Heat of absorption of CO2 in 30 wt% MEA with monoethyleneglycol and urea as vapour reduction additives

The heat of absorption is a critical thermodynamic property for establishing new solvents for CO2 capture. Experimental data for this thermodynamic property in the literature is limited. This study aims to determine the heat of absorption for new solvent compositions, which can potentially reduce energy consumption in solvent regeneration processes. The obtained heat of absorption data for CO2 in these solvents will contribute to the development of an Extended UNIQUAC model for the corresponding electrolyte system.

The heat of absorption of CO₂ was investigated in aqueous solvents containing 30 wt% MEA, 30 wt% MEA with 7.5 wt% MEG, 30 wt% MEA with 30 wt% MEG, and 30 wt% MEA with 7.5 wt% Urea. The measurements were conducted at 40 °C and 120 °C using a Setaram C-80 Calorimeter equipped with a mixing cell. MEG and Urea were included as vapour reduction additives (VRAs) due to their ability to lower the vapour pressure of the solvents.

The results show that the solvents containing 7.5 wt% and 30 wt% MEG exhibit higher heat of absorption compared to the aqueous 30 wt% MEA at 40 °C, with increases of 3.7% and 2.4%, respectively. However, at 120 °C, the heat of absorption is lower by 4.2% and 8.3% for the solvents with 7.5 wt% and 30 wt% MEG. In contrast, the solvent with 7.5 wt% Urea has a lower heat of absorption than the aqueous 30 wt% MEA, with reductions of 8.5% and 7.3% at 40 °C and 120 °C, respectively.