CO 2 solubility in aqueous binary mixtures of monoethanolamine, methyldiethanolamine, and diaminobutane

The main objective of this research is to improve the CO2 solubility and absorption rate of conventional alkanolamines including monoethanolamine (MEA) and methyldiethanolamine (MDEA) by 1,4–diaminobutane (DAB) as a promoter. Typically, the presence of two primary functional groups, lack of strict hindrance, and low molecular weight make DAB an efficient solvent to absorb CO2. In the first step, the absorption kinetic of DAB is investigated theoretically and a rate equation is proposed based on the zwitterion mechanism. In the second step, the equilibrium capacity of MEA and MDEA is promoted by DAB experiment in an isothermal stirred batch reactor in the pressure range 20–100 kPa, temperature range 303–313 K, and promoter volume fraction 0–10%. Then, the effective loading and regenerability of prepared samples are investigated by continuous cyclic absorption and regeneration in the designed reactor. The experimental results show that increasing DAB concentration in the MEA and MDEA as base solutions increases the CO2 absorption rate and equilibrium capacity. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.